Re-land "Only require that the stencil masks are same as many effective bits set" It seems reasonable to validate the equality between stencilWriteMask and stencilBackWriteMask only by comparing the effective bits. An existing dEQP test[1] and a WebGL test[2] also use the max size of stencil bits for checking the stencil mask values. [1] StencilWriteMaskSeparateTestCase (gles3/functional/ es3fIntegerStateQueryTests.cpp) [2] https://www.khronos.org/registry/webgl/sdk/tests/conformance/state/ gl-get-calls.html (Search for "minimumRequiredStencilMask ") Re-land with fix for Clang warning. Change-Id: I4cadaffced04ca55fa6daf7ac6a462368e0cfeec Reviewed-on: https://chromium-review.googlesource.com/307530 Reviewed-by: Jinyoung Hur <hurims@gmail.com> Reviewed-by: Geoff Lang <geofflang@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>