path ops stream-lining

src/pathops/SkPathOpsDebug.h

Index: src/pathops/SkPathOpsDebug.h
diff --git a/src/pathops/SkPathOpsDebug.h b/src/pathops/SkPathOpsDebug.h
index c1b1adb7072a750cf3e883cec1f8d3d9f2bf8171..5ea1dd8b2655a9993699140ad56b071d8f0e64ff 100644
--- a/src/pathops/SkPathOpsDebug.h
+++ b/src/pathops/SkPathOpsDebug.h
@@ -156,12 +156,19 @@
 #include "SkTLS.h"
 #endif
 
-#define FAIL_IF(cond) do { bool fail = (cond); SkOPASSERT(!fail); if (fail) return false; } \
-        while (false)
+// Tests with extreme numbers may fail, but all other tests should never fail.
+#define FAIL_IF(cond) \
+        do { bool fail = (cond); SkOPASSERT(!fail); if (fail) return false; } while (false)
 
+#define FAIL_WITH_NULL_IF(cond) \
+        do { bool fail = (cond); SkOPASSERT(!fail); if (fail) return nullptr; } while (false)
+
+// Some functions serve two masters: one allows the function to fail, the other expects success
+// always. If abort is true, tests with normal numbers may not fail and assert if they do so.
+// If abort is false, both normal and extreme numbers may return false without asserting.
 #define RETURN_FALSE_IF(abort, cond) \
-        do { bool fail = (cond); SkOPASSERT(!(abort) || !fail); if (fail) return false; } \
-        while (false)
+        do { bool fail = (cond); SkOPASSERT(!(abort) || !fail); if (fail) return false; \
+        } while (false)
 
 class SkPathOpsDebug {
 public: