Fix OOB problem in validationES.{h,cpp} maxVertexAttributes may less than the gl::MAX_VERTEX_ATTRIBS for some GLES2 devices, so using gl::MAX_VERTEX_ATTRIBS may cause OOB problem. Bug: chromium:1258869 Change-Id: I09609db35143fbf17b4228c7fe5f38a987e4f1d9 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3584637 Auto-Submit: Peng Huang <penghuang@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>