Revert of [typedarrays] move %TypedArray%.prototype.copyWithin to C++

src/js/typedarray.js

Index: src/js/typedarray.js
diff --git a/src/js/typedarray.js b/src/js/typedarray.js
index 6e8f3c76712845ae73812d87811e5a25e4e05e92..3a5cb847556176c9ea9d6672b8dfd3a0e0fde569 100644
--- a/src/js/typedarray.js
+++ b/src/js/typedarray.js
@@ -20,6 +20,7 @@ var GlobalArray = global.Array;
 var GlobalArrayBuffer = global.ArrayBuffer;
 var GlobalArrayBufferPrototype = GlobalArrayBuffer.prototype;
 var GlobalObject = global.Object;
+var InnerArrayCopyWithin;
 var InnerArrayEvery;
 var InnerArrayFill;
 var InnerArrayFilter;
@@ -67,6 +68,7 @@ utils.Import(function(from) {
   ArrayValues = from.ArrayValues;
   GetIterator = from.GetIterator;
   GetMethod = from.GetMethod;
+  InnerArrayCopyWithin = from.InnerArrayCopyWithin;
   InnerArrayEvery = from.InnerArrayEvery;
   InnerArrayFill = from.InnerArrayFill;
   InnerArrayFilter = from.InnerArrayFilter;
@@ -436,6 +438,17 @@ function TypedArrayGetToStringTag() {
 }
 
 
+function TypedArrayCopyWithin(target, start, end) {
+  if (!IS_TYPEDARRAY(this)) throw %make_type_error(kNotTypedArray);
+
+  var length = %_TypedArrayGetLength(this);
+
+  // TODO(littledan): Replace with a memcpy for better performance
+  return InnerArrayCopyWithin(target, start, end, this, length);
+}
+%FunctionSetLength(TypedArrayCopyWithin, 2);
+
+
 // ES6 draft 05-05-15, section 22.2.3.7
 function TypedArrayEvery(f, receiver) {
   if (!IS_TYPEDARRAY(this)) throw %make_type_error(kNotTypedArray);
@@ -845,6 +858,7 @@ utils.InstallGetter(GlobalTypedArray.prototype, toStringTagSymbol,
 utils.InstallFunctions(GlobalTypedArray.prototype, DONT_ENUM, [
   "subarray", TypedArraySubArray,
   "set", TypedArraySet,
+  "copyWithin", TypedArrayCopyWithin,
   "every", TypedArrayEvery,
   "fill", TypedArrayFill,
   "filter", TypedArrayFilter,