Fix errors from partial interface DedicatedWorkerGlobalScope

`: inheritance` part in a partial interface is a syntax error and `[Global]` on a partial interface is a semantics error. Having `[Exposed]` is not an error but is redundant.

Author: saschanaz

index.bs

@@ -277,8 +277,7 @@ interface RTCTransformEvent : Event {
     readonly attribute RTCRtpScriptTransformer transformer;
 };
 
-[Global=(Worker,DedicatedWorker),Exposed=DedicatedWorker]
-partial interface DedicatedWorkerGlobalScope : WorkerGlobalScope {
+partial interface DedicatedWorkerGlobalScope {
     attribute EventHandler onrtctransform;
 };