Don't make redundant calls to Display::makeCurrent. Refactor ValidateMakeCurrent to pass egl object pointers instead of handles. BUG=angleproject:2464 Change-Id: I98859f56d238a38bd6755f00dce7344635690491 Reviewed-on: https://chromium-review.googlesource.com/1053877 Commit-Queue: Geoff Lang <geofflang@chromium.org> Reviewed-by: Luc Ferron <lucferron@chromium.org>