When using the program binary memory cache inside ANGLE, this will
give a potential fast path. If the user doesn't query the shader
compile status or info log before calling LinkProgram, then we can
check the program cache before translating the program, and if it
finds a hit, we don't even need to call the translator.

To preserve the shader settings at compile time, a reference to the
current shader translator is kept in a binding pointer on the call
to compile. This mirrors a similar implementation in Chromium's
command buffer. Also the compile options and source are cached at
compile to preserve the correct shader state.

BUG=angleproject:1897

Change-Id: I3c046d7ac8c3b5c8cc169c4802ffe47f95537212
Reviewed-on: https://chromium-review.googlesource.com/517379Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>