* Fixes incorrect dirty checks for the dirty sampler mappings flag.
 * Fixes WebGL tests:
   * conformance_canvas_texture_bindings_unaffected_on_resize
   * conformance_reading_read_pixels_test
   * conformance_uniforms_uniform_default_values

BUG=414450

Change-Id: I132dbc301a236aef153fb6da4c6b64c36b0ba3f3
Reviewed-on: https://chromium-review.googlesource.com/218501Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>