Support event handling in SVG's use-element shadow trees

third_party/WebKit/Source/bindings/core/v8/V8LazyEventListener.h

Index: third_party/WebKit/Source/bindings/core/v8/V8LazyEventListener.h
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8LazyEventListener.h b/third_party/WebKit/Source/bindings/core/v8/V8LazyEventListener.h
index ccda256ce5352a2b3a7ac64d01ff29456b8f9a36..fa62f1d453137c9e11e1ce91e33810e58f780652 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8LazyEventListener.h
+++ b/third_party/WebKit/Source/bindings/core/v8/V8LazyEventListener.h
@@ -80,6 +80,10 @@ class V8LazyEventListener final : public V8AbstractEventListener {
                                             v8::Local<v8::Value>,
                                             Event*) override;
 
+  // Return true, so that event handlers from markup are not cloned twice when
+  // building the shadow tree for SVGUseElements.
+  bool wasCreatedFromMarkup() const override { return true; }
+
   void compileScript(ScriptState*, ExecutionContext*);
 
   void fireErrorEvent(v8::Local<v8::Context>,