Try hard to eliminate isError in ValidationEGL. We were getting a compile warning due to variable shadowing from redeclaring a local egl::Error. Fix this using the ANGLE_TRY macro. BUG=angleproject:596 Change-Id: I38954bd1c9f171f264d7ecbf58d634ae721296ad Reviewed-on: https://chromium-review.googlesource.com/346092 Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>