fix valgrind

src/pathops/SkPathOpsSimplify.cpp

Index: src/pathops/SkPathOpsSimplify.cpp
diff --git a/src/pathops/SkPathOpsSimplify.cpp b/src/pathops/SkPathOpsSimplify.cpp
index 90f75b98023e86d6b048a0b39e1dd67ddc607c59..b4f8e22142d459d1f7aa02fd7110f3f24a010dda 100644
--- a/src/pathops/SkPathOpsSimplify.cpp
+++ b/src/pathops/SkPathOpsSimplify.cpp
@@ -19,8 +19,8 @@ static bool bridgeWinding(SkTDArray<SkOpContour* >& contourList, SkPathWriter* s
     SkPoint lastTopLeft;
     SkPoint topLeft = {SK_ScalarMin, SK_ScalarMin};
     do {
-        SkOpSpanBase* start;
-        SkOpSpanBase* end;
+        SkOpSpanBase* start = NULL;
+        SkOpSpanBase* end = NULL;
         bool topDone;
         bool onlyVertical = false;
         lastTopLeft = topLeft;