Gave GrClip an SkClipStack-style iterator

http://codereview.appspot.com/6434046/



git-svn-id: http://skia.googlecode.com/svn/trunk@4723 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/core/SkClipStack.cpp b/src/core/SkClipStack.cpp
index 429d4c0..4212ba5 100644
--- a/src/core/SkClipStack.cpp
+++ b/src/core/SkClipStack.cpp
@@ -303,5 +303,6 @@
 }
 
 void SkClipStack::Iter::reset(const SkClipStack& stack, IterStart startLoc) {
+    fStack = &stack;
     fIter.reset(stack.fDeque, static_cast<SkDeque::Iter::IterStart>(startLoc));
 }