Followup to bug 555276: fix hacks in e10s.

dom/ipc/PContentProcess.ipdl

@@ -61,10 +61,6 @@ child:
 
     PTestShell();
 
-    // A dummy message to make sure PContentProcess contains methods to create
-    // Shmem segments.
-    async Dummy(Shmem foo);
-
     RegisterChrome(ChromePackage[] packages, ResourceMapping[] resources,
                    OverrideMapping[] overrides);