replace slice with a loop in rest parameters

lib/6to5/transformation/templates/rest.js

@@ -0,0 +1,3 @@
+for (var KEY = START; KEY < ARGUMENTS.length; KEY++) {
+  ARRAY[$__0] = ARGUMENTS[KEY];
+}

lib/6to5/transformation/transformers/es6-rest-parameters.js

@@ -1,6 +1,7 @@
-var t = require("../../types");
+var util = require("../../util");
+var t    = require("../../types");
 
-exports.Function = function (node, parent, file) {
+exports.Function = function (node, parent, file, scope) {
   if (!node.rest) return;
 
   var rest = node.rest;
@@ -8,15 +9,19 @@ exports.Function = function (node, parent, file) {
 
   t.ensureBlock(node);
 
-  var call = file.toArray(t.identifier("arguments"));
+  var argsId = t.identifier("arguments");
+  argsId._ignoreAliasFunctions = true;
 
-  if (node.params.length) {
-    call.arguments.push(t.literal(node.params.length));
-  }
+  node.body.body.unshift(
+    t.variableDeclaration("var", [
+      t.variableDeclarator(rest, t.arrayExpression([]))
+    ]),
 
-  call._ignoreAliasFunctions = true;
-
-  node.body.body.unshift(t.variableDeclaration("var", [
-    t.variableDeclarator(rest, call)
-  ]));
+    util.template("rest", {
+      ARGUMENTS: argsId,
+      START: t.literal(node.params.length),
+      ARRAY: rest,
+      KEY: file.generateUidIdentifier("key")
+    })
+  );
 };