path ops work in progress

BUG=

Review URL: https://codereview.chromium.org/18058007

git-svn-id: http://skia.googlecode.com/svn/trunk@9908 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/pathops/SkOpAngle.cpp b/src/pathops/SkOpAngle.cpp
index 0ac5a3d..0dd0d65 100644
--- a/src/pathops/SkOpAngle.cpp
+++ b/src/pathops/SkOpAngle.cpp
@@ -22,7 +22,7 @@
 
 #if DEBUG_ANGLE
     static bool CompareResult(SkString* bugOut, const char* append, bool compare) {
-        bugOut->appendf(append);
+        bugOut->appendf("%s", append);
         bugOut->writable_str()[bugChar] = "><"[compare];
         SkDebugf("%s\n", bugOut->c_str());
         return compare;
@@ -141,7 +141,7 @@
         }
     }
     if (fSide * rh.fSide == 0) {
-        SkASSERT(fSide + rh.fSide != 0);
+        SkASSERT(fSide + rh.fSide != 0); // hitting this assert means coincidence was undetected
         return COMPARE_RESULT("9 fSide * rh.fSide == 0 ...", fSide < rh.fSide);
     }
     // at this point, the initial tangent line is nearly coincident