Rename V8BindingMacros.

Rename macros defined in Source/bindings/v8/V8BindingMacros.h and do
some other refactorings in preparation for the upcoming code generator
change for APIs returning Promises.
This change doesn't change the behavior.

BUG=359386
R=nbarth@chromium.org

Review URL: https://codereview.chromium.org/298063007

git-svn-id: svn://svn.chromium.org/blink/trunk@174850 bbb929c8-8fbe-4397-9dbb-9b2b20218538