Fix SkNWayCanvas cons call when creating null canvas.

git-svn-id: http://skia.googlecode.com/svn/trunk@4223 2bbb7eff-a529-9590-31e7-b0007b416f81

src/utils/SkNullCanvas.cpp

@@ -14,5 +14,5 @@
 SkCanvas* SkCreateNullCanvas() {
     // An N-Way canvas forwards calls to N canvas's. When N == 0 it's
     // effectively a null canvas.
-    return SkNEW(SkNWayCanvas);
+    return SkNEW(SkNWayCanvas(0,0));
 }