SkCanvas::clear() should call down to devices even when the clip is empty.

src/core/SkCanvas.cpp

Index: src/core/SkCanvas.cpp
diff --git a/src/core/SkCanvas.cpp b/src/core/SkCanvas.cpp
index 4fda7a37b32a306aea9b229c083769acd44e0c1b..eb92585cafd5b525500e1405406492af1244a382 100644
--- a/src/core/SkCanvas.cpp
+++ b/src/core/SkCanvas.cpp
@@ -1702,7 +1702,7 @@ void SkCanvas::drawDRRect(const SkRRect& outer, const SkRRect& inner,
 //////////////////////////////////////////////////////////////////////////////
 
 void SkCanvas::clear(SkColor color) {
-    SkDrawIter  iter(this);
+    SkDrawIter  iter(this, false/*clear can affect empty clips*/);
     this->predrawNotify();
     while (iter.next()) {
         iter.fDevice->clear(color);