Dynamically generate image2D variables' declaration and function definition in libANGLE. Bug: angleproject:1987 TEST=angle_end2end_tests.ComputeShaderTest.* Change-Id: Idacc756f7bd15f22eccb1d689e18e997f3e74159 Reviewed-on: https://chromium-review.googlesource.com/c/1142885 Commit-Queue: Xinghua Cao <xinghua.cao@intel.com> Reviewed-by: Jamie Madill <jmadill@chromium.org>
