Reland "CreatePlatformGLTestContext_egl:  Try GLES 3, then GLES 2."

This is a reland of 0593a840b107c1abd312a03ef4000ddb58454f94

New functionality (which doesn't work everywhere) is behind a flag:
GR_EGL_TRY_GLES3_THEN_GLES2.

Original change's description:
> CreatePlatformGLTestContext_egl:  Try GLES 3, then GLES 2.
>
> Also cleanup.
>
> Change-Id: I186a7d7f509bc7852241c083414495b6182b916c
> Reviewed-on: https://skia-review.googlesource.com/115922
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Hal Canary <halcanary@google.com>

Change-Id: I362079dee9c74f1a2c31d935bcb821201a413923
Reviewed-on: https://skia-review.googlesource.com/116143
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
1 file changed