add isRect() check to AAClip, to detect if a soft-clip is really just an irect

src/core/SkRasterClip.cpp

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkRasterClip.h"
 
 
@@ skipping 204 matching lines @@
     }
     return fBW;
 }
 
 void SkRasterClip::convertToAA() {
     AUTO_RASTERCLIP_VALIDATE(*this);
 
     SkASSERT(fIsBW);
     fAA.setRegion(fBW);
     fIsBW = false;
-    (void)this->updateCacheAndReturnNonEmpty();
+    
+    // since we are being explicitly asked to convert-to-aa, we pass false so we don't "optimize"
+    // ourselves back to BW.
+    (void)this->updateCacheAndReturnNonEmpty(false);
 }
 
 #ifdef SK_DEBUG
 void SkRasterClip::validate() const {
     // can't ever assert that fBW is empty, since we may have called forceGetBW
     if (fIsBW) {
         SkASSERT(fAA.isEmpty());
     }
 
     fBW.validate();
@@ skipping 34 matching lines @@
         fBlitter = blitter;
     } else {
         const SkAAClip& aaclip = clip.aaRgn();
         fBWRgn.setRect(aaclip.getBounds());
         fAABlitter.init(blitter, &aaclip);
         // now our return values
         fClipRgn = &fBWRgn;
         fBlitter = &fAABlitter;
     }
 }