split tight quads and cubics

src/pathops/SkPathOpsTSect.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #ifndef SkPathOpsTSect_DEFINED
 #define SkPathOpsTSect_DEFINED
 
 #include "SkChunkAlloc.h"
@@ skipping 1513 matching lines @@
     double tStep = tEnd - tStart;
     SkDPoint workPt;
     do {
         tStep *= 0.5;
         if (precisely_zero(tStep)) {
             return 0;
         }
         workT += tStep;
         workPt = fCurve.ptAtT(workT);
         coinW.setPerp(fCurve, workT, workPt, opp->fCurve);
-        if (coinW.perpT() < 0) {
+        double perpT = coinW.perpT();
+        if (coinW.isCoincident() ? !between(oppSpan->fStartT, perpT, oppSpan->fEndT) : perpT < 0) {
             continue;
         }
         SkDVector perpW = workPt - coinW.perpPt();
         if ((perpS.dot(perpW) >= 0) == (tStep < 0)) {
             tStep = -tStep;
         }
         if (workPt.approximatelyEqual(coinW.perpPt())) {
             break;
         }
     } while (true);
@@ skipping 771 matching lines @@
             --last;
         } else {
             intersections->setCoincident(index++);
         }
         intersections->setCoincident(index);
     }
     SkASSERT(intersections->used() <= TCurve::kMaxIntersections);
 }
 
 #endif