Fix Windows build bustage. rs=brendan

js/src/shell/js.cpp

@@ -3596,7 +3596,7 @@ static JSFunctionSpec shell_functions[] = {
     JS_FS("help",           Help,           0,0,0),
     JS_FS("quit",           Quit,           0,0,0),
     JS_FN("assertEq",       AssertEq,       2,0),
-    JS_FN("gc",             GC,             0,0),
+    JS_FN("gc",             ::GC,           0,0),
     JS_FN("gcparam",        GCParameter,    2,0),
     JS_FN("countHeap",      CountHeap,      0,0),
 #ifdef JS_GC_ZEAL