Fix GpuDrawPathTest on ANGLE and enable it

tests/GpuDrawPathTest.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 "SkTypes.h"
 
 #if SK_SUPPORT_GPU
@@ skipping 57 matching lines @@
     oval2.addOval(rect, SkPath::kCCW_Direction);
 
     fill_and_stroke(canvas, oval1, oval2, nullptr);
 
     const SkScalar intervals[] = { 1, 1 };
     SkAutoTUnref<SkPathEffect> dashEffect(SkDashPathEffect::Create(intervals, 2, 0));
     fill_and_stroke(canvas, oval1, oval2, dashEffect);
 }
 
 DEF_GPUTEST(GpuDrawPath, reporter, factory) {
-    // https://bugs.chromium.org/p/skia/issues/detail?id=4581
-    return;
-
     for (int type = 0; type < GrContextFactory::kLastGLContextType; ++type) {
         GrContextFactory::GLContextType glType = static_cast<GrContextFactory::GLContextType>(type);
 
         GrContext* grContext = factory->get(glType);
         if (nullptr == grContext) {
             continue;
         }
         static const int sampleCounts[] = { 0, 4, 16 };
 
         for (size_t i = 0; i < SK_ARRAY_COUNT(sampleCounts); ++i) {
             SkImageInfo info = SkImageInfo::MakeN32Premul(255, 255);
             
             SkAutoTUnref<SkSurface> surface(
                 SkSurface::NewRenderTarget(grContext, SkSurface::kNo_Budgeted, info,
                                            sampleCounts[i], nullptr));
+            if (!surface) {
+                continue;
+            }
             test_drawPathEmpty(reporter, surface->getCanvas());
         }
     }
 }
 
 DEF_GPUTEST(GpuDrawPathSameRectOvals, reporter, factory) {
     GrContext* grContext = factory->get(GrContextFactory::kNVPR_GLContextType);
     if (!grContext) {
         return;
     }
 
     SkAutoTUnref<SkSurface> surface(
         SkSurface::NewRenderTarget(grContext, SkSurface::kNo_Budgeted,
                                    SkImageInfo::MakeN32Premul(255, 255), 4));
     test_drawSameRectOvals(reporter, surface->getCanvas());
 }
 
 #endif