Make SkTInternalLList::validate validate all nodes

Make SkTInternalLList::validate validate all nodes, including the
first one.

R=mtklein@google.com, bsalomon@google.com

Author: kkinnunen@nvidia.com

Review URL: https://codereview.chromium.org/104553002

git-svn-id: http://skia.googlecode.com/svn/trunk/include@12479 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/core/SkTInternalLList.h b/core/SkTInternalLList.h
index a6b6f15..0b67d4a 100644
--- a/core/SkTInternalLList.h
+++ b/core/SkTInternalLList.h
@@ -227,7 +227,7 @@
     void validate() const {
         SkASSERT(!fHead == !fTail);
         Iter iter;
-        for (T* item = iter.init(*this, Iter::kHead_IterStart); NULL != (item = iter.next()); ) {
+        for (T* item = iter.init(*this, Iter::kHead_IterStart); NULL != item; item = iter.next()) {
             SkASSERT(this->isInList(item));
             if (NULL == item->fPrev) {
                 SkASSERT(fHead == item);