Introduce TypeFeedbackVector, as FixedArray grew constrictive.

src/type-feedback-vector.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/objects.h"
+#include "src/type-feedback-vector.h"
+
+namespace v8 {
+namespace internal {
+
+// static
+Handle<TypeFeedbackVector> TypeFeedbackVector::Copy(
+    Isolate* isolate, Handle<TypeFeedbackVector> vector) {
+  Handle<TypeFeedbackVector> result;
+  result = Handle<TypeFeedbackVector>::cast(
+      isolate->factory()->CopyFixedArray(Handle<FixedArray>::cast(vector)));
+  return result;
+}
+}
+}  // namespace v8::internal