Sync various event interfaces with their specs

Source/core/events/MutationEvent.idl

Index: Source/core/events/MutationEvent.idl
diff --git a/Source/core/events/MutationEvent.idl b/Source/core/events/MutationEvent.idl
index 0aae4e31df94247d75cf26a374294aae883f39cc..9fde40fd2d5b41b08805b8664b07483a543e3c55 100644
--- a/Source/core/events/MutationEvent.idl
+++ b/Source/core/events/MutationEvent.idl
@@ -17,28 +17,26 @@
  * Boston, MA 02110-1301, USA.
  */
 
-// Introduced in DOM Level 2:
-interface MutationEvent : Event {
+// https://w3c.github.io/uievents/#interface-MutationEvent
 
+interface MutationEvent : Event {
     // attrChangeType
     const unsigned short MODIFICATION = 1;
     const unsigned short ADDITION     = 2;
     const unsigned short REMOVAL      = 3;
 
-    readonly attribute Node           relatedNode;
+    readonly attribute Node?          relatedNode;
     readonly attribute DOMString      prevValue;
     readonly attribute DOMString      newValue;
     readonly attribute DOMString      attrName;
     readonly attribute unsigned short attrChange;
-
-     void initMutationEvent([Default=Undefined] optional DOMString type,
-                                          [Default=Undefined] optional boolean canBubble,
+    // TODO(philipj): None of the initMutationEvent() arguments should be optional.
+    void initMutationEvent([Default=Undefined] optional DOMString type,
+                                          [Default=Undefined] optional boolean bubbles,
                                           [Default=Undefined] optional boolean cancelable,
                                           [Default=Undefined] optional Node relatedNode,
                                           [Default=Undefined] optional DOMString prevValue,
                                           [Default=Undefined] optional DOMString newValue,
                                           [Default=Undefined] optional DOMString attrName,
                                           [Default=Undefined] optional unsigned short attrChange);
-
 };
-