diff --git a/src/babel/transformation/file/index.js b/src/babel/transformation/file/index.js
index c3a0d4d424..aa4cb57b79 100644
--- a/src/babel/transformation/file/index.js
+++ b/src/babel/transformation/file/index.js
@@ -46,10 +46,9 @@ export default class File {
     this.data        = {};
     this.uids        = {};
 
-    this.lastStatements = [];
-    this.log            = new Logger(this, opts.filename || "unknown");
-    this.opts           = this.normalizeOptions(opts);
-    this.ast            = {};
+    this.log  = new Logger(this, opts.filename || "unknown");
+    this.opts = this.normalizeOptions(opts);
+    this.ast  = {};
 
     this.buildTransformers();
   }
@@ -375,10 +374,6 @@ export default class File {
     return id;
   }
 
-  isConsequenceExpressionStatement(node: Object): boolean {
-    return t.isExpressionStatement(node) && this.lastStatements.indexOf(node) >= 0;
-  }
-
   attachAuxiliaryComment(node: Object): Object {
     var comment = this.opts.auxiliaryComment;
     if (comment) {
@@ -479,9 +474,12 @@ export default class File {
     parseOpts.strictMode = features.strict;
     parseOpts.sourceType = "module";
 
+    this.log.debug("Parse start");
+
     //
 
     return parse(parseOpts, code, (tree) => {
+      this.log.debug("Parse stop");
       this.transform(tree);
       return this.generate();
     });
@@ -504,25 +502,25 @@ export default class File {
   }
 
   transform(ast) {
-    this.log.debug();
-
+    this.log.debug("Start set AST");
     this.setAst(ast);
+    this.log.debug("End set AST");
 
-    this.lastStatements = t.getLastStatements(ast.program);
+    this.log.debug("Start prepass");
+    //this.checkPath(this.path);
+    this.log.debug("End prepass");
 
+    this.log.debug("Start module formatter init");
     var modFormatter = this.moduleFormatter = this.getModuleFormatter(this.opts.modules);
     if (modFormatter.init && this.transformers["es6.modules"].canTransform()) {
       modFormatter.init();
     }
-
-    this.checkPath(this.path);
+    this.log.debug("End module formatter init");
 
     this.call("pre");
-
     each(this.transformerStack, function (pass) {
       pass.transform();
     });
-
     this.call("post");
   }
 
@@ -597,10 +595,14 @@ export default class File {
     if (opts.ast) result.ast = ast;
     if (!opts.code) return result;
 
+    this.log.debug("Generation start");
+
     var _result = generate(ast, opts, this.code);
     result.code = _result.code;
     result.map  = _result.map;
 
+    this.log.debug("Generation end");
+
     if (this.shebang) {
       // add back shebang
       result.code = `${this.shebang}\n${result.code}`;
diff --git a/src/babel/transformation/helpers/build-binary-assignment-operator-transformer.js b/src/babel/transformation/helpers/build-binary-assignment-operator-transformer.js
index b09292b3f3..04ffc4c1b3 100644
--- a/src/babel/transformation/helpers/build-binary-assignment-operator-transformer.js
+++ b/src/babel/transformation/helpers/build-binary-assignment-operator-transformer.js
@@ -12,7 +12,7 @@ export default function (exports, opts) {
 
   exports.ExpressionStatement = function (node, parent, scope, file) {
     // hit the `AssignmentExpression` one below
-    if (file.isConsequenceExpressionStatement(node)) return;
+    if (this.isCompletionRecord()) return;
 
     var expr = node.expression;
     if (!isAssignment(expr)) return;
diff --git a/src/babel/transformation/helpers/build-conditional-assignment-operator-transformer.js b/src/babel/transformation/helpers/build-conditional-assignment-operator-transformer.js
index 1cae5a8c4a..32cffe3245 100644
--- a/src/babel/transformation/helpers/build-conditional-assignment-operator-transformer.js
+++ b/src/babel/transformation/helpers/build-conditional-assignment-operator-transformer.js
@@ -8,7 +8,7 @@ export default function (exports, opts) {
 
   exports.ExpressionStatement = function (node, parent, scope, file) {
     // hit the `AssignmentExpression` one below
-    if (file.isConsequenceExpressionStatement(node)) return;
+    if (this.isCompletionRecord()) return;
 
     var expr = node.expression;
     if (!opts.is(expr, file)) return;
diff --git a/src/babel/transformation/helpers/name-method.js b/src/babel/transformation/helpers/name-method.js
index 8d3c7693d9..0dc3628a9d 100644
--- a/src/babel/transformation/helpers/name-method.js
+++ b/src/babel/transformation/helpers/name-method.js
@@ -82,7 +82,7 @@ var visit = function (node, name, scope) {
       // so we can safely just set the id and move along as it shadows the
       // bound function id
     }
-  } else {
+  } else if (state.outerDeclar || scope.hasGlobal(name)) {
     scope.traverse(node, visitor, state);
   }
 
@@ -104,7 +104,7 @@ export function property(node, file, scope) {
 
   var method = node.value;
   var state  = visit(method, name, scope);
-  node.value = wrap(state, method, id, scope);
+  node.value = wrap(state, method, id, scope) || method;
 }
 
 export function bare(node, parent, scope) {
@@ -128,7 +128,7 @@ export function bare(node, parent, scope) {
   } else if (t.isIdentifier(id)) {
     name = id.name;
   } else {
-    return;
+    return node;
   }
 
   name = t.toIdentifier(name);
diff --git a/src/babel/transformation/transformer-pass.js b/src/babel/transformation/transformer-pass.js
index f9de37890d..c6ce71f05a 100644
--- a/src/babel/transformation/transformer-pass.js
+++ b/src/babel/transformation/transformer-pass.js
@@ -46,21 +46,17 @@ export default class TransformerPass {
     var shouldVisit = this.transformer.shouldVisit;
     if (!shouldVisit) return;
 
-    var shouldSkip = !shouldVisit(path.node);
-    do {
-      if (path.getData(this.skipKey) !== false) {
-        path.setData(this.skipKey, shouldSkip);
-      }
-    } while(path = path.parentPath);
   }
 
   transform() {
     var file = this.file;
 
-    file.log.debug(`Running transformer ${this.transformer.key}`);
+    file.log.debug(`Start transformer ${this.transformer.key}`);
 
     traverse(file.ast, this.handlers, file.scope, file);
 
+    file.log.debug(`Finish transformer ${this.transformer.key}`);
+
     this.ran = true;
   }
 }
diff --git a/src/babel/transformation/transformers/es6/arrow-functions.js b/src/babel/transformation/transformers/es6/arrow-functions.js
index 33a4c10854..5c013af522 100644
--- a/src/babel/transformation/transformers/es6/arrow-functions.js
+++ b/src/babel/transformation/transformers/es6/arrow-functions.js
@@ -1,6 +1,6 @@
 import * as t from "../../../types";
 
-export var check = t.isArrowFunctionExpression;
+export var shouldVisit = t.isArrowFunctionExpression;
 
 export function ArrowFunctionExpression(node) {
   t.ensureBlock(node);
diff --git a/src/babel/transformation/transformers/es6/classes.js b/src/babel/transformation/transformers/es6/classes.js
index a17a2becff..12fb1765fe 100644
--- a/src/babel/transformation/transformers/es6/classes.js
+++ b/src/babel/transformation/transformers/es6/classes.js
@@ -11,7 +11,7 @@ import * as t from "../../../types";
 
 const PROPERTY_COLLISION_METHOD_NAME = "__initializeProperties";
 
-export var check = t.isClass;
+export var shouldVisit = t.isClass;
 
 export function ClassDeclaration(node, parent, scope, file) {
   return t.variableDeclaration("let", [
diff --git a/src/babel/transformation/transformers/es6/destructuring.js b/src/babel/transformation/transformers/es6/destructuring.js
index d36ba490cf..c6adc78b6c 100644
--- a/src/babel/transformation/transformers/es6/destructuring.js
+++ b/src/babel/transformation/transformers/es6/destructuring.js
@@ -1,7 +1,7 @@
 import * as messages from "../../../messages";
 import * as t from "../../../types";
 
-export var check = t.isPattern;
+export var shouldVisit = t.isPattern;
 
 export function ForOfStatement(node, parent, scope, file) {
   var left = node.left;
@@ -111,7 +111,7 @@ export function ExpressionStatement(node, parent, scope, file) {
   var expr = node.expression;
   if (expr.type !== "AssignmentExpression") return;
   if (!t.isPattern(expr.left)) return;
-  if (file.isConsequenceExpressionStatement(node)) return;
+  if (this.isCompletionRecord()) return;
 
   var destructuring = new DestructuringTransformer({
     operator: expr.operator,
diff --git a/src/babel/transformation/transformers/es6/for-of.js b/src/babel/transformation/transformers/es6/for-of.js
index 46b54a8be9..7d007d6465 100644
--- a/src/babel/transformation/transformers/es6/for-of.js
+++ b/src/babel/transformation/transformers/es6/for-of.js
@@ -2,7 +2,7 @@ import * as messages from "../../../messages";
 import * as util from  "../../../util";
 import * as t from "../../../types";
 
-export var check = t.isForOfStatement;
+export var shouldVisit = t.isForOfStatement;
 
 export function ForOfStatement(node, parent, scope, file) {
   if (this.get("right").isArrayExpression()) {
diff --git a/src/babel/transformation/transformers/es6/object-super.js b/src/babel/transformation/transformers/es6/object-super.js
index dce80dd2f1..7a08bdb3b3 100644
--- a/src/babel/transformation/transformers/es6/object-super.js
+++ b/src/babel/transformation/transformers/es6/object-super.js
@@ -1,7 +1,7 @@
 import ReplaceSupers from "../../helpers/replace-supers";
 import * as t from "../../../types";
 
-export var check = t.isSuper;
+export var shouldVisit = t.isSuper;
 
 function Property(path, node, scope, getObjectRef, file) {
   if (!node.method) return;
diff --git a/src/babel/transformation/transformers/es6/parameters.rest.js b/src/babel/transformation/transformers/es6/parameters.rest.js
index ed9d1c733c..94685ff293 100644
--- a/src/babel/transformation/transformers/es6/parameters.rest.js
+++ b/src/babel/transformation/transformers/es6/parameters.rest.js
@@ -2,7 +2,7 @@ import isNumber from "lodash/lang/isNumber";
 import * as util from  "../../../util";
 import * as t from "../../../types";
 
-export var check = t.isRestElement;
+export var shouldVisit = t.isRestElement;
 
 var memberExpressionOptimisationVisitor = {
   enter(node, parent, scope, state) {
diff --git a/src/babel/transformation/transformers/es6/spread.js b/src/babel/transformation/transformers/es6/spread.js
index 5d8abc2f74..a856453ed0 100644
--- a/src/babel/transformation/transformers/es6/spread.js
+++ b/src/babel/transformation/transformers/es6/spread.js
@@ -44,7 +44,7 @@ function build(props, scope) {
   return nodes;
 }
 
-export var check = t.isSpreadElement;
+export var shouldVisit = t.isSpreadElement;
 
 export function ArrayExpression(node, parent, scope) {
   var elements = node.elements;
diff --git a/src/babel/transformation/transformers/es7/do-expressions.js b/src/babel/transformation/transformers/es7/do-expressions.js
index 787dba3219..8f1e18875f 100644
--- a/src/babel/transformation/transformers/es7/do-expressions.js
+++ b/src/babel/transformation/transformers/es7/do-expressions.js
@@ -5,7 +5,7 @@ export var metadata = {
   stage: 0
 };
 
-export var check = t.isDoExpression;
+export var shouldVisit = t.isDoExpression;
 
 export function DoExpression(node) {
   var body = node.body.body;
diff --git a/src/babel/transformation/transformers/optimisation/flow.for-of.js b/src/babel/transformation/transformers/optimisation/flow.for-of.js
index 5e0237d700..a7bf59b174 100644
--- a/src/babel/transformation/transformers/optimisation/flow.for-of.js
+++ b/src/babel/transformation/transformers/optimisation/flow.for-of.js
@@ -1,7 +1,7 @@
 import { _ForOfStatementArray } from "../es6/for-of";
 import * as t from "../../../types";
 
-export var check = t.isForOfStatement;
+export var shouldVisit = t.isForOfStatement;
 export var optional = true;
 
 export function ForOfStatement(node, parent, scope, file) {
diff --git a/src/babel/transformation/transformers/validation/react.js b/src/babel/transformation/transformers/validation/react.js
index fd95e7a046..5666f8c299 100644
--- a/src/babel/transformation/transformers/validation/react.js
+++ b/src/babel/transformation/transformers/validation/react.js
@@ -1,6 +1,10 @@
 import * as messages from "../../../messages";
 import * as t from "../../../types";
 
+export var metadata = {
+  readOnly: true
+};
+
 export function shouldVisit(node) {
   return t.isModuleDeclaration(node) || (t.isCallExpression(node) && t.isIdentifier(node.callee, { name: "require" }));
 }
diff --git a/src/babel/transformation/transformers/validation/undeclared-variable-check.js b/src/babel/transformation/transformers/validation/undeclared-variable-check.js
index f8d3b25a78..01f1f4a86c 100644
--- a/src/babel/transformation/transformers/validation/undeclared-variable-check.js
+++ b/src/babel/transformation/transformers/validation/undeclared-variable-check.js
@@ -2,7 +2,8 @@ import levenshtein from "leven";
 import * as messages from "../../../messages";
 
 export var metadata = {
-  optional: true
+  optional: true,
+  readOnly: true
 };
 
 export function Identifier(node, parent, scope, file) {
diff --git a/src/babel/traversal/path/index.js b/src/babel/traversal/path/index.js
index f3401a2a20..267dbbd507 100644
--- a/src/babel/traversal/path/index.js
+++ b/src/babel/traversal/path/index.js
@@ -73,6 +73,7 @@ export default class TraversalPath {
 
     // we're entering a new scope so let's construct it!
     if (path.isScope()) {
+      var log = path.isProgram();
       ourScope = new Scope(path, scope, file);
     }
 
@@ -236,7 +237,10 @@ export default class TraversalPath {
 
     this.type = this.node && this.node.type;
 
+    var log = file && this.type === "Program";
+    if (log) file.log.debug("Start scope building");
     this.setScope(file);
+    if (log) file.log.debug("End scope building");
   }
 
   _remove() {
@@ -252,7 +256,7 @@ export default class TraversalPath {
     var removeParent = false;
     if (this.parentPath) {
       removeParent ||= this.parentPath.isExpressionStatement();
-      removeParent ||= this.parentPath.isSequenceExpression() && this.parent.expressions.length === 1
+      removeParent ||= this.parentPath.isSequenceExpression() && this.parent.expressions.length === 1;
       if (removeParent) return this.parentPath.remove();
     }
 
diff --git a/src/babel/traversal/scope.js b/src/babel/traversal/scope.js
index 87addd8627..f28592f337 100644
--- a/src/babel/traversal/scope.js
+++ b/src/babel/traversal/scope.js
@@ -681,7 +681,7 @@ export default class Scope {
    */
 
   removeOwnBinding(name: string) {
-    this.bindings[name] = null;
+    delete this.bindings[name];
   }
 
   /**
diff --git a/test/core/fixtures/transformation/es7.exponentian-operator/assignment/actual.js b/test/core/fixtures/transformation/es7.exponentian-operator/assignment/actual.js
index 3119676676..26439c4220 100644
--- a/test/core/fixtures/transformation/es7.exponentian-operator/assignment/actual.js
+++ b/test/core/fixtures/transformation/es7.exponentian-operator/assignment/actual.js
@@ -1,2 +1,3 @@
+var num = 1;
 num **= 2;
 ;
diff --git a/test/core/fixtures/transformation/es7.exponentian-operator/assignment/expected.js b/test/core/fixtures/transformation/es7.exponentian-operator/assignment/expected.js
index 771217952d..3cc44c2190 100644
--- a/test/core/fixtures/transformation/es7.exponentian-operator/assignment/expected.js
+++ b/test/core/fixtures/transformation/es7.exponentian-operator/assignment/expected.js
@@ -1,5 +1,6 @@
 "use strict";
 
+var num = 1;
 num = Math.pow(num, 2);
 
 ;
diff --git a/test/core/fixtures/transformation/spec.function-name/assignment/actual.js b/test/core/fixtures/transformation/spec.function-name/assignment/actual.js
index 584125ac2e..720d84e7de 100644
--- a/test/core/fixtures/transformation/spec.function-name/assignment/actual.js
+++ b/test/core/fixtures/transformation/spec.function-name/assignment/actual.js
@@ -4,4 +4,5 @@ var i = function () {
 
 var j = function () {
   ({ j } = 5);
+  ;
 };
diff --git a/test/core/fixtures/transformation/spec.function-name/assignment/expected.js b/test/core/fixtures/transformation/spec.function-name/assignment/expected.js
index be772c66d0..3c4aa618fd 100644
--- a/test/core/fixtures/transformation/spec.function-name/assignment/expected.js
+++ b/test/core/fixtures/transformation/spec.function-name/assignment/expected.js
@@ -17,4 +17,6 @@ var i = (function (_i) {
 var j = function j() {
   var _ = 5;
   j = _.j;
+
+  ;
 };