Now that libANGLE is cross-platform, this should work on OSX/Linux
and Android. Includes a warning fixes for test comparisons, and fix
to our META_ASSERT wrapper macro for clang.

BUG=angleproject:773

Change-Id: I6b88a85c62a2e07734ae81fb8276c28c5f8f9f47
Reviewed-on: https://chromium-review.googlesource.com/258300Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>