Fix Promise binding.

[1] introduced v8::Isolate* parameter to ScriptPromise constructor,
but it seems that fixing the code generator was missing.
This CL fixes it.

1: https://src.chromium.org/viewvc/blink?view=rev&revision=157950

R=haraken
BUG=263412

Review URL: https://codereview.chromium.org/145523008

git-svn-id: svn://svn.chromium.org/blink/trunk@165709 bbb929c8-8fbe-4397-9dbb-9b2b20218538