[SkSVGDevice] Initial clipping support

include/core/SkClipStack.h

Index: include/core/SkClipStack.h
diff --git a/include/core/SkClipStack.h b/include/core/SkClipStack.h
index 95e41e6220872aebbf64ccd106ee1a7ab96e9f9e..79789dcc268d80ad3c3b62bdd436063d5d2e45a0 100644
--- a/include/core/SkClipStack.h
+++ b/include/core/SkClipStack.h
@@ -323,6 +323,12 @@ public:
      */
     bool quickContains(const SkRect& devRect) const;
 
+    /**
+     * Flattens the clip stack into a single SkPath. Returns true if any of
+     * the clip stack components requires anti-aliasing.
+     */
+    bool asPath(SkPath* path) const;
+
     void clipDevRect(const SkIRect& ir, SkRegion::Op op) {
         SkRect r;
         r.set(ir);