Fixed two sub-optimal iterator uses

http://codereview.appspot.com/6409048/



git-svn-id: http://skia.googlecode.com/svn/trunk@4633 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/core/SkCanvas.cpp b/src/core/SkCanvas.cpp
index a65f454..567e5f5 100644
--- a/src/core/SkCanvas.cpp
+++ b/src/core/SkCanvas.cpp
@@ -534,8 +534,7 @@
 
 SkDevice* SkCanvas::getDevice() const {
     // return root device
-    SkDeque::F2BIter iter(fMCStack);
-    MCRec*           rec = (MCRec*)iter.next();
+    MCRec* rec = (MCRec*) fMCStack.front();
     SkASSERT(rec && rec->fLayer);
     return rec->fLayer->fDevice;
 }