remove unused variables

lib/6to5/transformation/transformers/generator-comprehension.js

@@ -1,7 +1,7 @@
 var arrayComprehension = require("./array-comprehension");
 var t                  = require("../../types");
 
-exports.ComprehensionExpression = function (node, parent, file) {
+exports.ComprehensionExpression = function (node) {
   if (!node.generator) return;
 
   var body = [];

lib/6to5/transformation/transformers/spread.js

@@ -1,8 +1,7 @@
-var util = require("../../util");
-var t    = require("../../types");
-var _    = require("lodash");
+var t = require("../../types");
+var _ = require("lodash");
 
-var getSpreadLiteral = function (spread, file) {
+var getSpreadLiteral = function (spread) {
   var literal = spread.argument;
   if (!t.isArrayExpression(literal)) {
     literal = t.callExpression(
@@ -38,7 +37,7 @@ var build = function (props, file) {
   _.each(props, function (prop) {
     if (t.isSpreadElement(prop)) {
       push();
-      nodes.push(getSpreadLiteral(prop, file));
+      nodes.push(getSpreadLiteral(prop));
     } else {
       _props.push(prop);
     }

lib/6to5/util.js

@@ -1,7 +1,6 @@
 require("./patch");
 
 var estraverse = require("estraverse");
-var transform  = require("./transformation/transform");
 var traverse   = require("./traverse");
 var acorn      = require("acorn-6to5");
 var path       = require("path");