Move global code for builtins into setup functions.

src/symbol.js

Index: src/symbol.js
diff --git a/src/symbol.js b/src/symbol.js
index fb7476f4383362925a020169427a75fbb02e0968..050e7d918a02e83934883f280ec75be9424ba9db 100644
--- a/src/symbol.js
+++ b/src/symbol.js
@@ -27,8 +27,14 @@
 
 "use strict";
 
+// This file relies on the fact that the following declaration has been made
+// in runtime.js:
+// var $Array = global.Array;
+
 var $Symbol = global.Symbol;
 
+// -------------------------------------------------------------------
+
 function SymbolConstructor(x) {
   var value =
     IS_SYMBOL(x) ? x : %CreateSymbol(IS_UNDEFINED(x) ? x : ToString(x));