Move the default return handling to please some versions of gcc.

TBR=ager@chromium.org
Review URL: http://codereview.chromium.org/125043

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2150 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/runtime.cc

@@ -6336,10 +6336,9 @@ class ScopeIterator {
         // Materialize the content of the closure scope into a JSObject.
         return MaterializeClosure(CurrentContext());
         break;
-      default:
-        UNREACHABLE();
-        return Handle<JSObject>();
     }
+    UNREACHABLE();
+    return Handle<JSObject>();
   }
 
   // Return the context for this scope. For the local context there might not