[bindings] Make all CustomEvent.initCustomEvent arguments non-optional and remove custom binding.

Source/core/events/CustomEvent.cpp

Index: Source/core/events/CustomEvent.cpp
diff --git a/Source/core/events/CustomEvent.cpp b/Source/core/events/CustomEvent.cpp
index 8fcd03d7a84f28349e0c0854fae6512336805a93..a9c87cbbdf8ef778d4d06ccfcbf882eef18a330c 100644
--- a/Source/core/events/CustomEvent.cpp
+++ b/Source/core/events/CustomEvent.cpp
@@ -45,6 +45,12 @@ CustomEvent::~CustomEvent()
 {
 }
 
+void CustomEvent::initCustomEvent(const AtomicString& type, bool canBubble, bool cancelable, const ScriptValue& detail)
+{
+    initEvent(type, canBubble, cancelable);
+    m_detail = detail;
+}
+
 void CustomEvent::initCustomEvent(const AtomicString& type, bool canBubble, bool cancelable, PassRefPtr<SerializedScriptValue> serializedDetail)
 {
     if (dispatched())