Prioritize reveal clipping over Outline clipping

bug:15780987
bug:17350602

Also update docs around clipping nesting behavior,
and some Z ordering behavior.

Change-Id: Iaa204350a0adfdcbd8c4b821fb4a9c0ae22f2613
diff --git a/libs/hwui/RenderNode.cpp b/libs/hwui/RenderNode.cpp
index 72786eb..7c29f48 100644
--- a/libs/hwui/RenderNode.cpp
+++ b/libs/hwui/RenderNode.cpp
@@ -405,7 +405,7 @@
         handler(op, PROPERTY_SAVECOUNT, properties().getClipToBounds());
     }
 
-    // TODO: support both reveal clip and outline clip simultaneously
+    // TODO: support nesting round rect clips
     if (mProperties.getRevealClip().willClip()) {
         Rect bounds;
         mProperties.getRevealClip().getBounds(&bounds);
@@ -413,7 +413,6 @@
     } else if (mProperties.getOutline().willClip()) {
         renderer.setClippingOutline(handler.allocator(), &(mProperties.getOutline()));
     }
-
 }
 
 /**