GLES1: Clip plane API and rendering

- Add unit tests for the API
- Update test expectations

+ Pass through point size from the vertex array to the shader,
required for new tests to pass.

BUG=angleproject:2306

Change-Id: Ib19436c1f4cb12873adea94f734c821363f9e27d
Reviewed-on: https://chromium-review.googlesource.com/1079993
Commit-Queue: Lingfeng Yang <lfy@google.com>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
diff --git a/src/libANGLE/validationES2.cpp b/src/libANGLE/validationES2.cpp
index cef4d26..dba4917 100644
--- a/src/libANGLE/validationES2.cpp
+++ b/src/libANGLE/validationES2.cpp
@@ -811,6 +811,12 @@
         case GL_NORMALIZE:
         case GL_RESCALE_NORMAL:
         case GL_COLOR_MATERIAL:
+        case GL_CLIP_PLANE0:
+        case GL_CLIP_PLANE1:
+        case GL_CLIP_PLANE2:
+        case GL_CLIP_PLANE3:
+        case GL_CLIP_PLANE4:
+        case GL_CLIP_PLANE5:
             return context->getClientVersion() < Version(2, 0);
         case GL_POINT_SIZE_ARRAY_OES:
             return context->getClientVersion() < Version(2, 0) &&