Fix two GL_OES_texture_half_float related problems with GLES2 * Fix incorrect ASSERT in formatutilsgl.cpp * CheckInternalFormatRenderbufferRenderability() and CheckSizedInternalFormatTextureRenderability() may cause GL errors, we should clear them. Bug: chromium:1174074 Change-Id: Ieef5e79b68f317833b459da34cc2e5362f813304 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2735374 Commit-Queue: Peng Huang <penghuang@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>