Fix assert caused by floating point error in tessellating path renderer.

tests/TessellatingPathRendererTests.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 "SkPath.h"
 
 #if SK_SUPPORT_GPU
@@ skipping 214 matching lines @@
 static SkPath create_path_15() {
     SkPath path;
     path.moveTo(    0.0f,   0.0f);
     path.lineTo(10000.0f,   0.0f);
     path.lineTo(    0.0f,  -1.0f);
     path.lineTo(10000.0f,   0.000001f);
     path.lineTo(    0.0f, -30.0f);
     return path;
 }
 
+// Reduction of Nebraska-StateSeal.svg. Floating point error causes the
+// same edge to be added to more than one poly on the same side.
+static SkPath create_path_16() {
+    SkPath path;
+    path.moveTo(170.8199920654296875,   491.86700439453125);
+    path.lineTo(173.7649993896484375,    489.7340087890625);
+    path.lineTo(174.1450958251953125,  498.545989990234375);
+    path.lineTo( 171.998992919921875,   500.88201904296875);
+    path.moveTo(168.2922515869140625,   498.66265869140625);
+    path.lineTo(169.8589935302734375,   497.94500732421875);
+    path.lineTo(                 172,   500.88299560546875);
+    path.moveTo( 169.555267333984375,   490.70111083984375);
+    path.lineTo(173.7649993896484375,    489.7340087890625);
+    path.lineTo(  170.82000732421875,   491.86700439453125);
+    return path;
+}
+
 static void test_path(GrDrawContext* drawContext, GrResourceProvider* rp, const SkPath& path) {
     GrTessellatingPathRenderer tess;
 
     GrPaint paint;
     paint.setXPFactory(GrPorterDuffXPFactory::Make(SkXfermode::kSrc_Mode));
 
     GrNoClip noClip;
     GrStyle style(SkStrokeRec::kFill_InitStyle);
     GrPathRenderer::DrawPathArgs args;
     args.fPaint = &paint;
@@ skipping 32 matching lines @@
     test_path(dc.get(), rp, create_path_6());
     test_path(dc.get(), rp, create_path_7());
     test_path(dc.get(), rp, create_path_8());
     test_path(dc.get(), rp, create_path_9());
     test_path(dc.get(), rp, create_path_10());
     test_path(dc.get(), rp, create_path_11());
     test_path(dc.get(), rp, create_path_12());
     test_path(dc.get(), rp, create_path_13());
     test_path(dc.get(), rp, create_path_14());
     test_path(dc.get(), rp, create_path_15());
+    test_path(dc.get(), rp, create_path_16());
 }
 #endif