Fix framebuffer completeness ES3 behavior.

Fix framebuffer completeness ES3 behavior.

In ES3, dimensions of images are no longer required to match.

BUG=429053
TEST=gpu_unittests, webgl_conformance2
R=piman@chromium.org

Committed: https://crrev.com/a0ee95ed8a530ebd2ee428162fa80ba47e72802c
Cr-Commit-Position: refs/heads/master@{#338420}

[Zhenyao Mo, 2015-07-10 23:50:39]

PTAL

[Zhenyao Mo, 2015-07-10 23:51:10]

With this CL, conformance2/renderbuffers/framebuffer-object-attachment.html
should pass

[piman, 2015-07-10 23:58:12]

LGTM, but can you add a test case for WEBGL2 contexts?

[Zhenyao Mo, 2015-07-11 00:28:46]

Added a unit test.  Do you wanna take another look?

[piman, 2015-07-11 00:36:02]

lgtm

[Zhenyao Mo, 2015-07-11 00:47:12]

The CQ bit was checked by zmo@chromium.org

[commit-bot: I haz the power, 2015-07-11 00:47:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1231273002/20001

[commit-bot: I haz the power, 2015-07-11 01:33:20]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-07-11 01:34:06]

Patchset 2 (id:??) landed as
https://crrev.com/a0ee95ed8a530ebd2ee428162fa80ba47e72802c
Cr-Commit-Position: refs/heads/master@{#338420}