Clean up the style in TextureStorage11. This is a pure refactoring change, and should behave identically. BUG=angleproject:1260 Change-Id: I44f5ef2f1444ffd8f8dd6ce55c266ec95781a6d8 Reviewed-on: https://chromium-review.googlesource.com/327266 Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>