Revert "Revert of Add getReducedClipStack to lua canvas (https://codereview.chromium.org/180283004/…

src/core/SkTLList.h

Index: src/core/SkTLList.h
diff --git a/src/core/SkTLList.h b/src/core/SkTLList.h
index 99b5bc67d964d2b6bc07584847993bafff925d71..aeae3f72eeb7f3c6b64be0f245e94c36b9ea2c1f 100644
--- a/src/core/SkTLList.h
+++ b/src/core/SkTLList.h
@@ -198,11 +198,11 @@ public:
 
         Iter() {}
 
-        Iter(const SkTLList& list, IterStart start) {
+        Iter(const SkTLList& list, IterStart start = kHead_IterStart) {
             INHERITED::init(list.fList, start);
         }
 
-        T* init(const SkTLList& list, IterStart start) {
+        T* init(const SkTLList& list, IterStart start = kHead_IterStart) {
             return this->nodeToObj(INHERITED::init(list.fList, start));
         }