Revert of Reopened: Caching the result of readPixelsSupported (https://codereview...

Revert of Reopened: Caching the result of readPixelsSupported (https://codereview.chromium.org/364193004/)

Reason for revert:
This appears to be causing failures on Android when running tests.

Original issue's description:
> Caching the result of readPixelsSupported
>
> The call was calling GR_GL_GetIntegerv 2 times for each readPixels
> and thus was causing a loss of performance
>
> (resubmit of issue 344793008)
>
> Benchmark url: http://packages.gkny.fr/tst/index.html
>
> BUG=skia:2681
>
> Committed: https://skia.googlesource.com/skia/+/753a2964afe5661ce9b2a8ca77ca9d0aabd3173c
>
> Committed: https://skia.googlesource.com/skia/+/8339371f1ec3c57a0741932fd96bff32c53d4e54

R=junov@chromium.org, reed@chromium.org, bsalomon@chromium.org, mtklein@google.com, bsalomon@google.com, piotaixr@chromium.org
TBR=bsalomon@chromium.org, bsalomon@google.com, junov@chromium.org, mtklein@google.com, piotaixr@chromium.org, reed@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=skia:2681

Author: bungeman@google.com

Review URL: https://codereview.chromium.org/395203002