Use angle::Result in front-end (Part 8) Refactors the gl::Texture class and a few related methods. Also reduces binary size by up to 4k. Bug: angleproject:2491 Change-Id: Ib9a69d7f507b0dce35abb17b90532f812bf43214 Reviewed-on: https://chromium-review.googlesource.com/c/1291845 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Yuly Novikov <ynovikov@chromium.org>