fix bugs found by computing flat clips in 800K skps

src/pathops/SkDQuadIntersection.cpp

Index: src/pathops/SkDQuadIntersection.cpp
diff --git a/src/pathops/SkDQuadIntersection.cpp b/src/pathops/SkDQuadIntersection.cpp
index 14ccac61869f89d7fddeff364001e6a2e17042a9..5a8bafcdc5631134cb30c02791a6628d37400f42 100644
--- a/src/pathops/SkDQuadIntersection.cpp
+++ b/src/pathops/SkDQuadIntersection.cpp
@@ -422,7 +422,7 @@ int SkIntersections::intersect(const SkDQuad& q1, const SkDQuad& q2) {
     swapped.setMax(fMax);
     if (is_linear(q2, q1, &swapped)) {
         swapped.swapPts();
-        set(swapped);
+        *this = swapped;
         return fUsed;
     }
     SkIntersections copyI(*this);