ES31: Add state change tests for image This change adds dirty bit state change tests for image textures. Meanwhile, syncImages related codes are removed since syncTextures will do all texture states sync. Bug: angleproject:3015 Change-Id: I9b299c86af1d589e72c08c5d7c55ac74cc7833aa Reviewed-on: https://chromium-review.googlesource.com/c/1390596 Commit-Queue: Jiajia Qin <jiajia.qin@intel.com> Reviewed-by: Jamie Madill <jmadill@chromium.org>