Add asADash entry point into SkPathEffect to allow extracting Dash info from PathEffects

src/core/SkPathEffect.cpp

Index: src/core/SkPathEffect.cpp
diff --git a/src/core/SkPathEffect.cpp b/src/core/SkPathEffect.cpp
index e1813203569f8a3f9035c74cfcab1c1275da333f..01d5d6f9619a98ab5dfa012b05293da205dfe896 100644
--- a/src/core/SkPathEffect.cpp
+++ b/src/core/SkPathEffect.cpp
@@ -22,6 +22,10 @@ bool SkPathEffect::asPoints(PointData* results, const SkPath& src,
     return false;
 }
 
+SkPathEffect::DashType SkPathEffect::asADash(DashInfo* info) const {
+    return kNone_DashType;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 SkPairPathEffect::SkPairPathEffect(SkPathEffect* pe0, SkPathEffect* pe1)