Reland: Remove "needkey" event and add its replacement, "encrypted".

Source/modules/encryptedmedia/MediaEncryptedEvent.idl

Index: Source/modules/encryptedmedia/MediaEncryptedEvent.idl
diff --git a/Source/modules/encryptedmedia/MediaKeyNeededEvent.idl b/Source/modules/encryptedmedia/MediaEncryptedEvent.idl
similarity index 91%
rename from Source/modules/encryptedmedia/MediaKeyNeededEvent.idl
rename to Source/modules/encryptedmedia/MediaEncryptedEvent.idl
index c99a180b5e19e0f54eb9b594bb8312c74201b30c..186deb7df8be50755e3111a6caea99bf56f0c2be 100644
--- a/Source/modules/encryptedmedia/MediaKeyNeededEvent.idl
+++ b/Source/modules/encryptedmedia/MediaEncryptedEvent.idl
@@ -26,8 +26,8 @@
 [
     EventConstructor,
     RuntimeEnabled=EncryptedMedia
-] interface MediaKeyNeededEvent : Event {
-    readonly attribute DOMString contentType;
-    readonly attribute Uint8Array initData;
+] interface MediaEncryptedEvent : Event {
+    readonly attribute DOMString initDataType;
+    readonly attribute ArrayBuffer? initData;
 };