GitLab

This moves the null-check out into generated bindings code.
The test canvas/philip/tests/2d.imageData.create1.zero.html is (minimally)
adjusted to match the revised upstream WPT test.

Review URL: https://codereview.chromium.org/237063003

git-svn-id: svn://svn.chromium.org/blink/trunk@171484 bbb929c8-8fbe-4397-9dbb-9b2b20218538