add SkRect::joinNonEmptyArg for faster unioning

src/gpu/GrDistanceFieldTextContext.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 "GrDistanceFieldTextContext.h"
 #include "GrAtlas.h"
 #include "GrDrawTarget.h"
@@ skipping 393 matching lines @@
     SkFixed ty = SkIntToFixed(glyph->fAtlasLocation.fY + SK_DistanceFieldInset);
     SkFixed tw = SkIntToFixed(glyph->fBounds.width() - 2*SK_DistanceFieldInset);
     SkFixed th = SkIntToFixed(glyph->fBounds.height() - 2*SK_DistanceFieldInset);
 
     SkRect r;
     r.fLeft = sx;
     r.fTop = sy;
     r.fRight = sx + width;
     r.fBottom = sy + height;
 
-    fVertexBounds.growToInclude(r);
+    fVertexBounds.joinNonEmptyArg(r);
 
     size_t vertSize = fUseLCDText ? (2 * sizeof(SkPoint))
                                   : (2 * sizeof(SkPoint) + sizeof(GrColor));
 
     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 243 matching lines @@
                                       SkScalarToFixed(x) - (glyph.fAdvanceX >> alignShift),
                                       SkScalarToFixed(y) - (glyph.fAdvanceY >> alignShift),
                                       fontScaler);
             }
             pos += scalarsPerPosition;
         }
     }
 
     this->finish();
 }