Texture data initialization happens after dirty bit synchronization so
TextureGL::initializeContents must be careful to leave the applied state the
same way it found it.

BUG=angleproject:3703

Change-Id: I1647cfc59c45fd9fad0fcde2e37af831e56f2e57
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1704215Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>
Commit-Queue: Geoff Lang <geofflang@chromium.org>