Check for ANGLE's implementation of texture_rectangle

ANGLE has implemented extension to support for texture_rectangle. Check
for its existence as well as GL_ARB_texture_rectangle extension.

Intended to follow up on Chrome side to avoid copy into texture 2d for
PaintCanvasVideoRenderer.

Bug: skia:7903
Change-Id: I450aa7fcd08628831251a9e142fd50719723282d
Reviewed-on: https://skia-review.googlesource.com/130962
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Weiliang Chen <weiliangc@chromium.org>
4 files changed