Improve creating external array buffer in d8.

src/d8.cc

Index: src/d8.cc
diff --git a/src/d8.cc b/src/d8.cc
index 976510c464009a19f91bc9e7a0101decdc536fe4..ce2afd34d4b483d61165316e9ad1c1209ac4b7f9 100644
--- a/src/d8.cc
+++ b/src/d8.cc
@@ -488,14 +488,7 @@ Handle<Value> Shell::CreateExternalArray(const Arguments& args,
     byteLength = length * element_size;
     byteOffset = 0;
 
-    Handle<Object> global = Context::GetCurrent()->Global();
-    Handle<Value> array_buffer = global->Get(String::New("ArrayBuffer"));
-    ASSERT(!try_catch.HasCaught() && array_buffer->IsFunction());
-    Handle<Value> buffer_args[] = { Uint32::New(byteLength) };
-    Handle<Value> result = Handle<Function>::Cast(array_buffer)->NewInstance(
-        1, buffer_args);
-    if (try_catch.HasCaught()) return result;
-    buffer = result->ToObject();
+    buffer = CreateExternalArrayBuffer(Object::New(), byteLength)->ToObject();
   }
 
   Handle<Object> array = CreateExternalArray(