pathops: Split loop type cubics only when there is a self-intersection.

src/pathops/SkPathOpsCubic.cpp

Index: src/pathops/SkPathOpsCubic.cpp
diff --git a/src/pathops/SkPathOpsCubic.cpp b/src/pathops/SkPathOpsCubic.cpp
index 2542ca58848c9e7da4834b165473c1f71ed3bc83..c511d0da50eab2b51bab9fa3edefc83a8fded5ed 100644
--- a/src/pathops/SkPathOpsCubic.cpp
+++ b/src/pathops/SkPathOpsCubic.cpp
@@ -240,13 +240,13 @@ bool SkDCubic::ComplexBreak(const SkPoint pointsPtr[4], SkScalar* t) {
         SkScalar lt = 2.f * d[0];
         SkScalar ms = d[1] + tempSqrt;
         SkScalar mt = 2.f * d[0];
-        if (between(0, ls, lt) || between(0, ms, mt)) {
+        if (between(0, ls, lt) && between(0, ms, mt)) {  // Both in [0, 1] interval.
             ls = ls / lt;
             ms = ms / mt;
-            SkScalar smaller = SkTMax(0.f, SkTMin(ls, ms));
-            SkScalar larger = SkTMin(1.f, SkTMax(ls, ms));
-            *t = (smaller + larger) / 2;
-            return *t > 0 && *t < 1;
+            SkASSERT(ls >= 0 && ls <= 1 && ms >= 0 && ms <= 1);  // Both in [0, 1].

[caryclark, 2016/04/25 14:46:30]

use between, e.g.:
 SkASSERT(between(0, ls, 1) && between(0, ms, 1));

+            *t = (ls + ms) / 2;
+            SkASSERT(*t >= 0 && *t <= 1);  // Average should also be in [0, 1].

[caryclark, 2016/04/25 14:46:30]

use between

+            return *t > 0 && *t < 1;  // Check that the cut isn't on an endpoint.

[caryclark, 2016/04/25 14:46:30]

use zero_or_one(t)

         }
     } else if (kSerpentine_SkCubicType == cubicType || kCusp_SkCubicType == cubicType) {
         SkDCubic cubic;