simplify bug

The path contains a cubic with a very tight curve.
Split the cubic into pieces so that the individual
curves are better behaved.

Use both inflections and max curvature to 
potentially split cubics. Since this may require
a bit of work, preflight to ignore cubics that
monotonically change in x and y.

Only one of the three tests referred to by the bug
below repro'd. Use path.dumpHex() instead of 
path.dump() to capture the crashing data.

TBR=reed@google.com
BUG=skia:6041

Change-Id: I29a264f87242cacc7c421e7685b90aca81621c74
Reviewed-on: https://skia-review.googlesource.com/5702
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Cary Clark <caryclark@google.com>
diff --git a/tests/PathOpsOpTest.cpp b/tests/PathOpsOpTest.cpp
index 6825095..2da0d4c 100644
--- a/tests/PathOpsOpTest.cpp
+++ b/tests/PathOpsOpTest.cpp
@@ -3847,10 +3847,10 @@
 #include "SkGeometry.h"
 
 static void complex_to_quads(const SkPoint pts[], SkPath* path) {
-    SkScalar loopT;
-    if (SkDCubic::ComplexBreak(pts, &loopT)) {
+    SkScalar loopT[3];
+    if (SkDCubic::ComplexBreak(pts, loopT)) {
         SkPoint cubicPair[7];
-        SkChopCubicAt(pts, cubicPair, loopT);
+        SkChopCubicAt(pts, cubicPair, loopT[0]);
         SkDCubic c1, c2;
         c1.set(cubicPair);
         c2.set(&cubicPair[3]);