Pass isolate to v8::False() / v8::True() when possible

Pass isolate to v8::False() / v8::True() when possible to avoid implicit call to
v8::Isolate::GetCurrent().

R=haraken
BUG=

Review URL: https://chromiumcodereview.appspot.com/23619034

git-svn-id: svn://svn.chromium.org/blink/trunk@157675 bbb929c8-8fbe-4397-9dbb-9b2b20218538