fix path op conic bugs

src/pathops/SkPathOpsConic.cpp

Index: src/pathops/SkPathOpsConic.cpp
diff --git a/src/pathops/SkPathOpsConic.cpp b/src/pathops/SkPathOpsConic.cpp
index f80af036ee20fdd29cfc08bf369c3be21a2c1e78..86bad262e32ba4f72ac7f9949f4556ab814efce9 100644
--- a/src/pathops/SkPathOpsConic.cpp
+++ b/src/pathops/SkPathOpsConic.cpp
@@ -153,13 +153,8 @@ SkDConic SkDConic::subDivide(double t1, double t2) const {
     double bx = 2 * dx - (ax + cx) / 2;
     double by = 2 * dy - (ay + cy) / 2;
     double bz = 2 * dz - (az + cz) / 2;
-    SkDConic dst = {{{{ax / az, ay / az}, {bx / bz, by / bz}, {cx / cz, cy / cz}}}, 0 };
-    SkDPoint dMidAC = { (dst.fPts[0].fX + dst.fPts[2].fX) / 2,
-                        (dst.fPts[0].fY + dst.fPts[2].fY) / 2 };
-    SkDPoint dMid = { dx / dz, dy / dz };
-    SkDVector dWNumer = dMidAC - dMid;
-    SkDVector dWDenom = dMid - dst.fPts[1];
-    dst.fWeight = dWNumer.length() / dWDenom.length();
+    SkDConic dst = {{{{ax / az, ay / az}, {bx / bz, by / bz}, {cx / cz, cy / cz}}},
+            SkDoubleToScalar(bz / sqrt(az * cz)) };
     return dst;
 }