ES 2.0 is feature complete.

Passes all of the angle_end2end_tests with the new linear command
recording method. Also runs the T-Rex benchmark without any obvious
glitches. Likely has issues with creating too many RenderPasses. ES3
is mostly untouched.

Bug: angleproject:4029
Change-Id: Ic5acf3d768495fbffd07b07bf0a6f2b5787c51f8
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2012900Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>