This fixes cases where pre-rotation wasn't occuring for small scissors
used with glClear().  There are around 1000 tests that do this.

Test: angle_deqp_gles2_tests --gtest_filter=dEQP.GLES2/functional_fragment_ops_depth_stencil_*
Bug: angleproject:4431
Bug: b/157933235
Bug: b/157933198
Change-Id: I469d51975e3bc3a7bfc9521a3817c919e809f7dd
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2228211Reviewed-by: Cody Northrop <cnorthrop@google.com>
Commit-Queue: Ian Elliott <ianelliott@google.com>