Update ANGLE to latest as of August 25, 2016

Update ANGLE to latest as of August 25, 2016

With this version, it's now exposing GL_EXT_color_buffer_half_float, but
it's (incorrectly) using GL_HALF_FLOAT rather than GL_HALF_FLOAT_OES.
In addition, release builds were crashing in EGLImageTest due to an
apparent disagreement about calling convention on function-pointer to
exported symbol. There is a proper typedef for that in one of their
headers, but I can't seem to include it without creating more problems,
so I just fixed the decoration on our local typedef.

With those changes, all tests pass, and (on my Windows machine), all
GMs and SKPs produce identical results vs. master in angle and angle-gl.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2282733003

Review-Url: https://codereview.chromium.org/2282733003