The fix is to skip updates that are queued that are not valid for the
current image description. We keep these around in case they are used
in a later usage of the same texture but we issue a warning telling the
user that memory will be used indefinitely until they use that data.

Bug: angleproject:2596
Change-Id: I8c20fffbd473ae8e2e9d2123a49b675b824a9bf6
Reviewed-on: https://chromium-review.googlesource.com/1078913Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Luc Ferron <lucferron@chromium.org>