Set empty/wide-open genID on clip stack in more places and fix a bug in GrReduceClipStack.

R=robertphillips@google.com
Review URL: https://codereview.appspot.com/6847116

git-svn-id: http://skia.googlecode.com/svn/trunk@6579 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests/ClipStackTest.cpp b/tests/ClipStackTest.cpp
index 2707e40..8eb1102 100644
--- a/tests/ClipStackTest.cpp
+++ b/tests/ClipStackTest.cpp
@@ -903,7 +903,7 @@
     test_rect_merging(reporter);
     test_iter_rect_merging(reporter);
 #if SK_SUPPORT_GPU
-    //test_reduced_clip_stack(reporter);
+    test_reduced_clip_stack(reporter);
 #endif
 }