Add some bench tests for various GPU data copies for Canvas/WebGL to catch performance improvements and regressions

BUG=242244

Review URL: https://chromiumcodereview.appspot.com/19607004

git-svn-id: svn://svn.chromium.org/blink/trunk@155664 bbb929c8-8fbe-4397-9dbb-9b2b20218538