Reset conicWeights in SkPath::consumeDegenerateSegments when rewinding to last Move op

Without this patch the iterator can end up running off the end of the conic weights if there is a mixture of degenerate and non-degenerate ops

Note: we might want to suppress the generation of degenerate conics and lines in SkPath::addRRect

BUG=459897

Review URL: https://codereview.chromium.org/954453003
diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp
index de3d297..0b796fc 100644
--- a/src/core/SkPath.cpp
+++ b/src/core/SkPath.cpp
@@ -1660,6 +1660,7 @@
     // forward before the next move is seen
     const uint8_t* lastMoveVerb = 0;
     const SkPoint* lastMovePt = 0;
+    const SkScalar* lastMoveWeight = NULL;
     SkPoint lastPt = fLastPt;
     while (fVerbs != fVerbStop) {
         unsigned verb = *(fVerbs - 1); // fVerbs is one beyond the current verb
@@ -1668,6 +1669,7 @@
                 // Keep a record of this most recent move
                 lastMoveVerb = fVerbs;
                 lastMovePt = fPts;
+                lastMoveWeight = fConicWeights;
                 lastPt = fPts[0];
                 fVerbs--;
                 fPts++;
@@ -1688,6 +1690,7 @@
                     if (lastMoveVerb) {
                         fVerbs = lastMoveVerb;
                         fPts = lastMovePt;
+                        fConicWeights = lastMoveWeight;
                         return;
                     }
                     return;
@@ -1703,6 +1706,7 @@
                     if (lastMoveVerb) {
                         fVerbs = lastMoveVerb;
                         fPts = lastMovePt;
+                        fConicWeights = lastMoveWeight;
                         return;
                     }
                     return;
@@ -1718,6 +1722,7 @@
                     if (lastMoveVerb) {
                         fVerbs = lastMoveVerb;
                         fPts = lastMovePt;
+                        fConicWeights = lastMoveWeight;
                         return;
                     }
                     return;