Use event init dictionaries in modules/{notifications,push_messaging,serviceworkers}

Source/modules/push_messaging/PushEvent.cpp

Index: Source/modules/push_messaging/PushEvent.cpp
diff --git a/Source/modules/push_messaging/PushEvent.cpp b/Source/modules/push_messaging/PushEvent.cpp
index 06dbc4676297cecd0d74da6b8a5ce2cd0e4edb87..5c0d4d03b8c5492ef38bab3a77114298c0693649 100644
--- a/Source/modules/push_messaging/PushEvent.cpp
+++ b/Source/modules/push_messaging/PushEvent.cpp
@@ -7,10 +7,6 @@
 
 namespace blink {
 
-PushEventInit::PushEventInit()
-{
-}
-
 PushEvent::PushEvent()
 {
 }
@@ -23,8 +19,9 @@ PushEvent::PushEvent(const AtomicString& type, PushMessageData* data, WaitUntilO
 
 PushEvent::PushEvent(const AtomicString& type, const PushEventInit& initializer)
     : ExtendableEvent(type, initializer)
-    , m_data(initializer.data)
 {
+    if (initializer.hasData())
+        m_data = initializer.data();
 }
 
 PushEvent::~PushEvent()