Make one copy for all TypedArray methods

src/typedarray.js

Index: src/typedarray.js
diff --git a/src/typedarray.js b/src/typedarray.js
index 926920427275132efa4ead35d2a634b1d1dd656c..372dd511bee72ea0febc9b406da88f6516c2457f 100644
--- a/src/typedarray.js
+++ b/src/typedarray.js
@@ -153,10 +153,11 @@ function NAME_GetLength() {
   }
   return %_TypedArrayGetLength(this);
 }
+endmacro
 
-function NAMESubArray(begin, end) {
-  if (!(%_ClassOf(this) === 'NAME')) {
-    throw MakeTypeError(kIncompatibleMethodReceiver, "NAME.subarray", this);
+function TypedArraySubArray(begin, end) {

[adamk, 2015/05/08 01:13:34]

We probably want to change this in the future, but I'd like to limit the changes
you're making in this one to what's behind the --harmony-arrays flag (and thus
won't affect what we're currently shipping).

+  if (!%IsTypedArray(this)) {
+    throw MakeTypeError('not_typed_array', []);
   }
   var beginInt = TO_INTEGER(begin);
   if (!IS_UNDEFINED(end)) {
@@ -181,11 +182,10 @@ function NAMESubArray(begin, end) {
   }
   var newLength = endInt - beginInt;
   var beginByteOffset =
-      %_ArrayBufferViewGetByteOffset(this) + beginInt * ELEMENT_SIZE;
-  return new GlobalNAME(%TypedArrayGetBuffer(this),
-                        beginByteOffset, newLength);
+      %_ArrayBufferViewGetByteOffset(this) + beginInt * this.BYTES_PER_ELEMENT;
+  return new this.constructor(%TypedArrayGetBuffer(this),
+                              beginByteOffset, newLength);
 }
-endmacro
 
 TYPED_ARRAYS(TYPED_ARRAY_CONSTRUCTOR)
 
@@ -322,7 +322,7 @@ macro SETUP_TYPED_ARRAY(ARRAY_ID, NAME, ELEMENT_SIZE)
   $installGetter(GlobalNAME.prototype, symbolToStringTag,
                  TypedArrayGetToStringTag);
   $installFunctions(GlobalNAME.prototype, DONT_ENUM, [
-    "subarray", NAMESubArray,
+    "subarray", TypedArraySubArray,
     "set", TypedArraySet
   ]);
 endmacro