fix debug version of cubicpair detected by asan

src/pathops/SkPathOpsCubic.h

Index: src/pathops/SkPathOpsCubic.h
diff --git a/src/pathops/SkPathOpsCubic.h b/src/pathops/SkPathOpsCubic.h
index f868fbe2c7d8895f44f0cbf78f92c97b3268bffe..61de48d19cd085748cf9f9c529b4643bd33fb122 100644
--- a/src/pathops/SkPathOpsCubic.h
+++ b/src/pathops/SkPathOpsCubic.h
@@ -11,11 +11,7 @@
 #include "SkPath.h"
 #include "SkPathOpsPoint.h"
 
-struct SkDCubicPair {
-    const SkDCubic& first() const { return (const SkDCubic&) pts[0]; }
-    const SkDCubic& second() const { return (const SkDCubic&) pts[3]; }
-    SkDPoint pts[7];
-};
+struct SkDCubicPair;
 
 struct SkDCubic {
     static const int kPointCount = 4;
@@ -157,4 +153,26 @@ inline int other_two(int one, int two) {
     return 1 >> (3 - (one ^ two)) ^ 3;
 }
 
+struct SkDCubicPair {
+    const SkDCubic first() const {
+#ifdef SK_DEBUG
+        SkDCubic result;
+        result.debugSet(&pts[0]);
+        return result;
+#else
+        return (const SkDCubic&) pts[0];
+#endif
+    }
+    const SkDCubic second() const {
+#ifdef SK_DEBUG
+        SkDCubic result;
+        result.debugSet(&pts[3]);
+        return result;
+#else
+        return (const SkDCubic&) pts[3];
+#endif
+    }
+    SkDPoint pts[7];
+};
+
 #endif