Presentation API: mark session required in PresentationSessionConnectEventInit.

See spec change: https://github.com/w3c/presentation-api/issues/184

BUG=529051

Review URL: https://codereview.chromium.org/1311003004

git-svn-id: svn://svn.chromium.org/blink/trunk@201971 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/modules/presentation/PresentationSessionConnectEvent.idl

@@ -5,7 +5,7 @@
 // https://w3c.github.io/presentation-api/#interface-presentationsessionconnectevent
 
 [
-    Constructor(DOMString type, optional PresentationSessionConnectEventInit eventInitDict),
+    Constructor(DOMString type, PresentationSessionConnectEventInit eventInitDict),
     RuntimeEnabled=Presentation
 ] interface PresentationSessionConnectEvent : Event {
     [SameObject] readonly attribute PresentationSession session;

third_party/WebKit/Source/modules/presentation/PresentationSessionConnectEventInit.idl

@@ -5,5 +5,5 @@
 // https://w3c.github.io/presentation-api/#idl-def-presentationsessionconnecteventinit
 
 dictionary PresentationSessionConnectEventInit : EventInit {
-    PresentationSession session;
+    required PresentationSession session;
 };