The staged resource updates adjusted their level to take base level into
account, but clear updates used a cached unadjusted value.

Bug: angleproject:3148
Change-Id: I9a49d5341083b2f870baa1ee6053e54baef35086
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2230786
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Cody Northrop <cnorthrop@google.com>