some pathops fuzz fixes

R=kjlubick@google.com
Bug: skia:
Change-Id: I0b2089f728f91ef5af780d0e9f91d266c252c054
Reviewed-on: https://skia-review.googlesource.com/c/169341
Auto-Submit: Cary Clark <caryclark@skia.org>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>

src/pathops/SkOpCoincidence.cpp

@@ -860,7 +860,7 @@ bool SkOpCoincidence::addMissing(bool* added  DEBUG_COIN_DECLARE_PARAMS()) {
                 }
             } else if (outerOpp == innerCoin) {
                 const SkOpPtT* ooe = outer->oppPtTEnd();
-                SkASSERT(!ooe->deleted());
+                FAIL_IF(ooe->deleted());
                 const SkOpPtT* ice = inner->coinPtTEnd();
                 SkASSERT(!ice->deleted());
                 SkASSERT(outerCoin != innerOpp);

src/pathops/SkPathOpsAsWinding.cpp

@@ -260,7 +260,7 @@ public:
         return winding;
     }
 
-    void containerContains(Contour& contour, Contour& test) {
+    bool containerContains(Contour& contour, Contour& test) {
         // find outside point on lesser contour
         // arbitrarily, choose non-horizontal edge where point <= bounds left
         // note that if leftmost point is control point, may need tight bounds
@@ -273,8 +273,8 @@ public:
         int winding = this->nextEdge(contour, Edge::kCompare);
         // if edge is up, mark contour cw, otherwise, ccw
         // sum of greater edges direction should be cw, 0, ccw
-        SkASSERT(-1 <= winding && winding <= 1);
         test.fContained = winding != 0;
+        return -1 <= winding && winding <= 1;
     }
 
     void inParent(Contour& contour, Contour& parent) {
@@ -297,13 +297,18 @@ public:
         parent.fChildren.push_back(&contour);
     }
 
-    void checkContainerChildren(Contour* parent, Contour* child) {
+    bool checkContainerChildren(Contour* parent, Contour* child) {
         for (auto grandChild : child->fChildren) {
-            checkContainerChildren(child, grandChild);
+            if (!checkContainerChildren(child, grandChild)) {
+                return false;
+            }
         }
         if (parent) {
-            containerContains(*parent, *child);
+            if (!containerContains(*parent, *child)) {
+                return false;
+            }
         }
+        return true;
     }
 
     bool markReverse(Contour* parent, Contour* child) {
@@ -402,7 +407,9 @@ bool SK_API AsWinding(const SkPath& path, SkPath* result) {
     // starting with outermost and moving inward, see if one path contains another
     for (auto contour : sorted.fChildren) {
         winder.nextEdge(*contour, OpAsWinding::Edge::kInitial);
-        winder.checkContainerChildren(nullptr, contour);
+        if (!winder.checkContainerChildren(nullptr, contour)) {
+            return false;
+        }
     }
     // starting with outermost and moving inward, mark paths to reverse
     bool reversed = false;

src/pathops/SkPathOpsSimplify.cpp

@@ -122,12 +122,12 @@ static bool bridgeXor(SkOpContourHead* contourList, SkPathWriter* writer) {
             start = nextStart;
             end = nextEnd;
         } while (!writer->isClosed() && (!unsortable || !start->starter(end)->done()));
-#ifdef SK_DEBUG
         if (!writer->isClosed()) {
             SkOpSpan* spanStart = start->starter(end);
-            SkASSERT(spanStart->done());
+            if (!spanStart->done()) {
+                return false;
+            }
         }
-#endif
         writer->finishContour();
         SkPathOpsDebug::ShowActiveSpans(contourList);
     } while (true);

src/pathops/SkPathOpsTSect.cpp

@@ -997,7 +997,9 @@ int SkTSect::intersects(SkTSpan* span,
                 hullResult = 1;
             }
             if (!oppSpan->fBounded || !oppSpan->fBounded->fNext) {
-                SkASSERT(!oppSpan->fBounded || oppSpan->fBounded->fBounded == span);
+                if (oppSpan->fBounded && oppSpan->fBounded->fBounded != span) {
+                    return 0;
+                }
                 if (oppStart) {
                     oppSpan->fEndT = oppSpan->fStartT;
                 } else {

src/pathops/SkPathWriter.cpp

@@ -354,7 +354,9 @@ void SkPathWriter::assemble() {
             const SkPath& contour = fPartials[rIndex];
             if (!first) {
                 SkPoint prior, next;
-                SkAssertResult(fPathPtr->getLastPt(&prior));
+                if (!fPathPtr->getLastPt(&prior)) {
+                    return;
+                }
                 if (forward) {
                     next = contour.getPoint(0);
                 } else {