Fixed an assertion error in GrAAConvexTessellator. While adding a new point, it would check that th…

src/gpu/batches/GrAAConvexTessellator.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 "GrAAConvexTessellator.h"
 #include "SkCanvas.h"
 #include "SkPath.h"
@@ skipping 817 matching lines @@
         return;
     }
 
     SkASSERT(fPts.count() <= 1 || fPts.count() == fNorms.count()+1);
     if (this->numPts() >= 2 && 
         abs_dist_from_line(fPts.top(), fNorms.top(), p) < kClose) {
         // The old last point is on the line from the second to last to the new point
         this->popLastPt();
         fNorms.pop();
         fIsCurve.pop();
+        // double-check that the new last point is not a duplicate of the new point. In an ideal
+        // world this wouldn't be necessary (since it's only possible for non-convex paths), but
+        // floating point precision issues mean it can actually happen on paths that were determined
+        // to be convex.
+        if (duplicate_pt(p, this->lastPoint())) {
+            return;
+        }
     }
     SkScalar initialRingCoverage = fStrokeWidth < 0.0f ? 0.5f : 1.0f;
     this->addPt(p, 0.0f, initialRingCoverage, false, isCurve);
     if (this->numPts() > 1) {
         *fNorms.push() = fPts.top() - fPts[fPts.count()-2];
         SkDEBUGCODE(SkScalar len =) SkPoint::Normalize(&fNorms.top());
         SkASSERT(len > 0.0f);
         SkASSERT(SkScalarNearlyEqual(1.0f, fNorms.top().length()));
     }
 }
@@ skipping 170 matching lines @@
         SkString num;
         num.printf("%d", i);
         canvas->drawText(num.c_str(), num.size(), 
                          this->point(i).fX, this->point(i).fY+(kPointRadius/2.0f), 
                          paint);
     }
 }
 
 #endif