add SkRect::joinNonEmptyArg for faster unioning

src/gpu/GrBitmapTextContext.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrBitmapTextContext.h"
 #include "GrAtlas.h"
 #include "GrDrawTarget.h"
@@ skipping 557 matching lines @@
 
     SkFixed tx = SkIntToFixed(glyph->fAtlasLocation.fX);
     SkFixed ty = SkIntToFixed(glyph->fAtlasLocation.fY);
 
     SkRect r;
     r.fLeft = SkFixedToFloat(vx);
     r.fTop = SkFixedToFloat(vy);
     r.fRight = SkFixedToFloat(vx + width);
     r.fBottom = SkFixedToFloat(vy + height);
 
-    fVertexBounds.growToInclude(r);
+    fVertexBounds.joinNonEmptyArg(r);
 
     size_t vertSize = useColorVerts ? (2 * sizeof(SkPoint) + sizeof(GrColor)) :
                                       (2 * sizeof(SkPoint));
 
     SkASSERT(vertSize == fDrawTarget->getDrawState().getVertexStride());
 
     SkPoint* positions = reinterpret_cast<SkPoint*>(
         reinterpret_cast<intptr_t>(fVertices) + vertSize * fCurrVertex);
     positions->setRectFan(r.fLeft, r.fTop, r.fRight, r.fBottom, vertSize);
 
@@ skipping 11 matching lines @@
         }
         // color comes after position.
         GrColor* colors = reinterpret_cast<GrColor*>(positions + 1);
         for (int i = 0; i < 4; ++i) {
            *colors = fPaint.getColor();
            colors = reinterpret_cast<GrColor*>(reinterpret_cast<intptr_t>(colors) + vertSize);
         }
     }
     fCurrVertex += 4;
 }