chore: cleanup unused WebContents::DereferenceRemoteJSObject() (#24167)

shell/common/api/api.mojom

@@ -72,13 +72,6 @@ interface ElectronBrowser {
     string channel,
     blink.mojom.CloneableMessage arguments);
 
-  // This is an API specific to the "remote" module, and will ultimately be
-  // replaced by generic IPC once WeakRef is generally available.
-  [EnableIf=enable_remote_module]
-  DereferenceRemoteJSObject(
-    string context_id,
-    int32 object_id);
-
   UpdateDraggableRegions(
     array<DraggableRegion> regions);