Unify internal and external typed arrays a bit

src/runtime/runtime-typedarray.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/arguments.h"
 #include "src/runtime/runtime.h"
 #include "src/runtime/runtime-utils.h"
 
@@ skipping 223 matching lines @@
     holder->set_buffer(*buffer);
 
     Handle<ExternalArray> elements = isolate->factory()->NewExternalArray(
         static_cast<int>(length), array_type,
         static_cast<uint8_t*>(buffer->backing_store()) + byte_offset);
     Handle<Map> map =
         JSObject::GetElementsTransitionMap(holder, external_elements_kind);
     JSObject::SetMapAndElements(holder, map, elements);
     DCHECK(IsExternalArrayElementsKind(holder->map()->elements_kind()));
   } else {
-    holder->set_buffer(Smi::FromInt(0));
+    Handle<JSArrayBuffer> buffer = isolate->factory()->NewJSArrayBuffer();
+    Runtime::SetupArrayBuffer(isolate, buffer, true, NULL, byte_length);
+    holder->set_buffer(*buffer);
     Handle<FixedTypedArrayBase> elements =
         isolate->factory()->NewFixedTypedArray(static_cast<int>(length),
                                                array_type);
     holder->set_elements(*elements);
   }
   return isolate->heap()->undefined_value();
 }
 
 
 // Initializes a typed array from an array-like object.
@@ skipping 462 matching lines @@
 DATA_VIEW_SETTER(Uint16, uint16_t)
 DATA_VIEW_SETTER(Int16, int16_t)
 DATA_VIEW_SETTER(Uint32, uint32_t)
 DATA_VIEW_SETTER(Int32, int32_t)
 DATA_VIEW_SETTER(Float32, float)
 DATA_VIEW_SETTER(Float64, double)
 
 #undef DATA_VIEW_SETTER
 }
 }  // namespace v8::internal