Presentation API: startSession() no longer takes a presentation id.

Source/modules/presentation/Presentation.idl

Index: Source/modules/presentation/Presentation.idl
diff --git a/Source/modules/presentation/Presentation.idl b/Source/modules/presentation/Presentation.idl
index 58094291617f7ada1a1261c1617dbbb1faa9a09e..2ec7725fde5ed4f6ae21fb6faeac3b57c4c42357 100644
--- a/Source/modules/presentation/Presentation.idl
+++ b/Source/modules/presentation/Presentation.idl
@@ -9,8 +9,7 @@
     RuntimeEnabled=Presentation
 ] interface Presentation : EventTarget {
     // This API used by controlling browsing context.
-    // TODO(avayvod): The |presentationId| argument is not in the spec.
-    [CallWith=ScriptState] Promise<PresentationSession> startSession(DOMString url, [Default=Undefined] optional DOMString presentationId);
+    [CallWith=ScriptState] Promise<PresentationSession> startSession(DOMString url);
     // TODO(avayvod): The |presentationId| argument should not be optional.
     [CallWith=ScriptState] Promise<PresentationSession> joinSession(DOMString url, [Default=Undefined] optional DOMString presentationId);
     [CallWith=ScriptState] Promise<PresentationAvailability> getAvailability(DOMString url);