Removed local variables 'isolate' to make the code generation simpler.
Update Blink binding test result files accordingly.

Follow-up issue of Issue 352353002. https://codereview.chromium.org/352353002/

BUG=378191

Review URL: https://codereview.chromium.org/367963002

git-svn-id: svn://svn.chromium.org/blink/trunk@178138 bbb929c8-8fbe-4397-9dbb-9b2b20218538