speed up debug dm

src/core/SkPathMeasure.cpp

 /*
  * Copyright 2008 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkPathMeasure.h"
 #include "SkPathMeasurePriv.h"
@@ skipping 389 matching lines @@
     fLength = distance;
     fIsClosed = isClosed;
     fFirstPtIndex = ptIndex;
 
 #ifdef SK_DEBUG
     {
         const Segment* seg = fSegments.begin();
         const Segment* stop = fSegments.end();
         unsigned        ptIndex = 0;
         SkScalar        distance = 0;
-
+        // limit the loop to a reasonable number; pathological cases can run for minutes
+        int             maxChecks = 10000000;  // set to INT_MAX to defeat the check
         while (seg < stop) {
             SkASSERT(seg->fDistance > distance);
             SkASSERT(seg->fPtIndex >= ptIndex);
             SkASSERT(seg->fTValue > 0);
 
             const Segment* s = seg;
-            while (s < stop - 1 && s[0].fPtIndex == s[1].fPtIndex) {
+            while (s < stop - 1 && s[0].fPtIndex == s[1].fPtIndex && --maxChecks > 0) {
                 SkASSERT(s[0].fType == s[1].fType);
                 SkASSERT(s[0].fTValue < s[1].fTValue);
                 s += 1;
             }
 
             distance = seg->fDistance;
             ptIndex = seg->fPtIndex;
             seg += 1;
         }
     //  SkDebugf("\n");
@@ skipping 268 matching lines @@
 
     for (int i = 0; i < fSegments.count(); i++) {
         const Segment* seg = &fSegments[i];
         SkDebugf("pathmeas: seg[%d] distance=%g, point=%d, t=%g, type=%d\n",
                 i, seg->fDistance, seg->fPtIndex, seg->getScalarT(),
                  seg->fType);
     }
 }
 
 #endif