Add a centralized workarounds module. This is a temporary home for the various workarounds we use for performance or to solve driver issues. Eventually we will want a standalone library we can use as part of Chromium or in ANGLE standalone. BUG=angle:729 Change-Id: Ib0254262cad9f8fb779886dacb967be646ea96ae Reviewed-on: https://chromium-review.googlesource.com/219838 Reviewed-by: Brandon Jones <bajones@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>