Disable GL_MULTISAMPLE when it's not being used

src/gpu/GrPipelineBuilder.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrPipelineBuilder.h"
 
 #include "GrBatch.h"
@@ skipping 56 matching lines @@
     this->setRenderTarget(rt);
 
     // These have no equivalent in GrPaint, set them to defaults
     fDrawFace = kBoth_DrawFace;
     fStencilSettings.setDisabled();
     fFlagBits = 0;
 
     fClip = clip;
 
     this->setState(GrPipelineBuilder::kDither_StateBit, paint.isDither());
-    this->setState(GrPipelineBuilder::kHWAntialias_StateBit, paint.isAntiAlias());
+    this->setState(GrPipelineBuilder::kHWAntialias_StateBit,
+                   rt->isMultisampled() && paint.isAntiAlias());
 
     fColorProcInfoValid = false;
     fCoverageProcInfoValid = false;
 
     fColorCache = GrColor_ILLEGAL;
     fCoverageCache = GrColor_ILLEGAL;
 }
 
 //////////////////////////////////////////////////////////////////////////////s
 
@@ skipping 88 matching lines @@
 void GrPipelineBuilder::calcCoverageInvariantOutput(GrColor coverage) const {
     if (!fCoverageProcInfoValid || coverage != fCoverageCache) {
         GrColorComponentFlags flags = kRGBA_GrColorComponentFlags;
         fCoverageProcInfo.calcWithInitialValues(fCoverageStages.begin(),
                                                 this->numCoverageFragmentStages(), coverage, flags,
                                                 true);
         fCoverageProcInfoValid = true;
         fCoverageCache = coverage;
     }
 }