Add once field to devtools so it can be queried by lighthouse.

third_party/WebKit/Source/bindings/core/v8/V8EventListenerInfo.h

Index: third_party/WebKit/Source/bindings/core/v8/V8EventListenerInfo.h
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8EventListenerInfo.h b/third_party/WebKit/Source/bindings/core/v8/V8EventListenerInfo.h
index ea53dc1627fcf3be221fabaf8e86bb35d973342d..c39b7c68d3ee67647218d3607bf1f7774714fd63 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8EventListenerInfo.h
+++ b/third_party/WebKit/Source/bindings/core/v8/V8EventListenerInfo.h
@@ -17,17 +17,20 @@ class V8EventListenerInfo {
   V8EventListenerInfo(AtomicString eventType,
                       bool useCapture,
                       bool passive,
+                      bool once,
                       v8::Local<v8::Object> handler,
                       v8::MaybeLocal<v8::Function> removeFunction)
       : eventType(eventType),
         useCapture(useCapture),
         passive(passive),
+        once(once),
         handler(handler),
         removeFunction(removeFunction) {}
 
   AtomicString eventType;
   bool useCapture;
   bool passive;
+  bool once;
   v8::Local<v8::Object> handler;
   v8::MaybeLocal<v8::Function> removeFunction;
 };