Bug 1016539. Add support for accelerated a11y filters. r=mwoodrow

This adds the ability to render to a temporary surface and use that
to apply a filter effect to all of the content.

gfx/layers/opengl/OGLShaderProgram.cpp

@@ -47,6 +47,8 @@ AddUniforms(ProgramProfileOGL& aProfile)
         "uRenderColor",
         "uTexCoordMultiplier",
         "uTexturePass2",
+        "uColorMatrix",
+        "uColorMatrixVector",
         nullptr
     };