allow one zero length dash

tests/DashPathEffectTest.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "Test.h"
 
 #include "SkDashPathEffect.h"
 #include "SkWriteBuffer.h"
 #include "SkStrokeRec.h"
 
 // crbug.com/348821 was rooted in SkDashPathEffect refusing to flatten and unflatten itself when
-// fInitialDashLength < 0 (a signal the effect is nonsense).  Here we test that it flattens.
+// the effect is nonsense.  Here we test that it fails when passed nonsense parameters.
 
 DEF_TEST(DashPathEffectTest_crbug_348821, r) {
     SkScalar intervals[] = { 1.76934361e+36f, 2.80259693e-45f };  // Values from bug.
     const int count = 2;
-    SkScalar phase = SK_ScalarInfinity;  // Used to force the bad fInitialDashLength = -1 path.
+    SkScalar phase = SK_ScalarInfinity;  // Used to force a nonsense effect.
     SkAutoTUnref<SkPathEffect> dash(SkDashPathEffect::Create(intervals, count, phase));
 
-    // nullptr -> refuses to work with flattening framework.
-    REPORTER_ASSERT(r, dash->getFactory() != nullptr);
-
-    SkWriteBuffer buffer;
-    buffer.writeFlattenable(dash);
-    REPORTER_ASSERT(r, buffer.bytesWritten() > 12);  // We'd write 12 if broken, >=40 if not.
+    REPORTER_ASSERT(r, dash == nullptr);
 }
 
 // Test out the asPoint culling behavior.
 DEF_TEST(DashPathEffectTest_asPoints, r) {
 
     const SkScalar intervals[] = { 1.0f, 1.0f };
     const int count = 2;
     SkAutoTUnref<SkPathEffect> dash(SkDashPathEffect::Create(intervals, count, 0.0f));
 
     SkRect cull = SkRect::MakeWH(1.0f, 1.0f);
@@ skipping 58 matching lines @@
     SkScalar intervals[2] = { 1, 1 };
     SkAutoTUnref<SkPathEffect> dash(SkDashPathEffect::Create(intervals, 2, 0));
 
     SkPaint paint;
     paint.setStyle(SkPaint::kStroke_Style);
     paint.setPathEffect(dash);
 
     SkPath fill;
     paint.getFillPath(path, &fill);
 }