pathops coincidence and security rewrite

src/pathops/SkPathOpsCubic.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkGeometry.h"
 #include "SkLineParameters.h"
 #include "SkPathOpsConic.h"
 #include "SkPathOpsCubic.h"
@@ skipping 259 matching lines @@
                 SkDebugf("maxCurvature[%d]=%1.9g ", index, maxCurvature[index]);
                 SkDPoint pt = cubic.ptAtT(maxCurvature[index]);
                 SkDVector dPt = cubic.dxdyAtT(maxCurvature[index]);
                 SkDLine perp = {{pt - dPt, pt + dPt}};
                 perp.dump();
             }
 #endif
             for (int index = 0; index < roots; ++index) {
                 if (between(inflectionTs[0], maxCurvature[index], inflectionTs[1])) {
                     *t = maxCurvature[index];
-                    return true;
+                    return *t > 0 && *t < 1;
                 }
             }
         } else if (infTCount == 1) {
             *t = inflectionTs[0];
             return *t > 0 && *t < 1;
         }
     }
     return false;
 }
 
@@ skipping 399 matching lines @@
     for (int index = 0; index < roots; ++index) {
         double t = startT + (endT - startT) * extremeTs[index];
         SkDPoint mid = dCurve.ptAtT(t);
         if (topPt->fY > mid.fY || (topPt->fY == mid.fY && topPt->fX > mid.fX)) {
             topT = t;
             *topPt = mid;
         }
     }
     return topT;
 }