Revert of [es6] Match ArrayBuffer constructor behavior of Firefox. (patchset...

Revert of [es6] Match ArrayBuffer constructor behavior of Firefox. (patchset #1 id:1 of https://codereview.chromium.org/1497163002/ )

Reason for revert:
Blocks the roll:
https://codereview.chromium.org/1497763004/

Original issue's description:
> [es6] Match ArrayBuffer constructor behavior of Firefox.
>
> We choose to deliberately violate the ES2015 specification and implement
> the ArrayBuffer constructor in a way that matches Firefox and Safari
> instead.
>
> BUG=v8:4592
> LOG=n
>
> Committed: https://crrev.com/8aae841ce26f01f3535e54af3a58fb7c65833eb7
> Cr-Commit-Position: refs/heads/master@{#32597}

TBR=jarin@chromium.org,bmeurer@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4592

Review URL: https://codereview.chromium.org/1496293002

Cr-Commit-Position: refs/heads/master@{#32605}

src/builtins.cc

@@ -1781,7 +1781,7 @@ BUILTIN(ArrayBufferConstructor_ConstructStub) {
   isolate->set_context(args.target()->context());
   Handle<Object> number_length;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, number_length,
-                                     Object::ToInteger(isolate, length));
+                                     Object::ToNumber(length));
   size_t byte_length;
   if (!TryNumberToSize(isolate, *number_length, &byte_length)) {
     THROW_NEW_ERROR_RETURN_FAILURE(