fix texture size check in WindowSurfaceCGL::swap BUG=angleproject:1233 Change-Id: I92fddf331fe0687b290606fe222863bd0fcbc2da Reviewed-on: https://chromium-review.googlesource.com/329804 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org>