path ops -- fix skp bugs

This fixes a series of bugs discovered by running
the small set of Skia skp files through pathops
to flatten the clips.
Review URL: https://codereview.chromium.org/14798004

git-svn-id: http://skia.googlecode.com/svn/trunk@9042 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/pathops/SkPathOpsSimplify.cpp b/src/pathops/SkPathOpsSimplify.cpp
index cb00aff..9a319e0 100644
--- a/src/pathops/SkPathOpsSimplify.cpp
+++ b/src/pathops/SkPathOpsSimplify.cpp
@@ -32,11 +32,15 @@
         do {
             if (current->activeWinding(index, endIndex)) {
                 do {
-            #if DEBUG_ACTIVE_SPANS
                     if (!unsortable && current->done()) {
+            #if DEBUG_ACTIVE_SPANS
                         DebugShowActiveSpans(contourList);
-                    }
             #endif
+                        if (simple->isEmpty()) {
+                            simple->init();
+                            break;
+                        }
+                    }
                     SkASSERT(unsortable || !current->done());
                     int nextStart = index;
                     int nextEnd = endIndex;
@@ -63,7 +67,7 @@
                 } while (!simple->isClosed() && (!unsortable
                         || !current->done(SkMin32(index, endIndex))));
                 if (current->activeWinding(index, endIndex) && !simple->isClosed()) {
-                    SkASSERT(unsortable);
+                    SkASSERT(unsortable || simple->isEmpty());
                     int min = SkMin32(index, endIndex);
                     if (!current->done(min)) {
                         current->addCurveTo(index, endIndex, simple, true);
@@ -182,7 +186,7 @@
     CoincidenceCheck(&contourList, 0);
     FixOtherTIndex(&contourList);
     SortSegments(&contourList);
-#if DEBUG_ACTIVE_SPANS
+#if DEBUG_ACTIVE_SPANS || DEBUG_ACTIVE_SPANS_FIRST_ONLY
     DebugShowActiveSpans(contourList);
 #endif
     // construct closed contours