The dEQP-GLES2.functional.fbo.render.texsubimage.between_render_tex2d*
test was failing because a TexSubImage call modifying the framebuffer
wasn't being applied before a subsequent DrawElements call and thus
getting an incorrect result.

Bug: angleproject:3249
Test: angle_deqp_gles2_tests --gtest_filter=dEQP.GLES2/functional_fbo_render_texsubimage_between_render_tex2d_rgb --use-angle=vulkan
Change-Id: I90f791957e6536c5c62fb731d52cd486ab5c05c1
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1542361
Commit-Queue: Courtney Goeltzenleuchter <courtneygo@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>