This adds a new C++ API method

```cpp
Local<Object> Object::New(
  Isolate* isolate,
  Local<Value> prototype_or_null,
  Local<Name>* keys,
  Local<Value>* values,
  size_t size);
```

which is similar to the `Object.create()` builtin exposed by JavaScript.
This new API is supposed to be used by the `http2` (in Node.js) to speed
up the creation of the HTTP header object.

Bug: v8:8422
Change-Id: I9910e88de0af2cbd8ce8a1d6cb6caa9451fb8cb4
Design-Document: http://bit.ly/v8-fast-object-create-cpp
Reviewed-on: https://chromium-review.googlesource.com/c/1337569
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57570}