Move error message makers off js builtins object.

src/debug/mirrors.js

Index: src/debug/mirrors.js
diff --git a/src/debug/mirrors.js b/src/debug/mirrors.js
index bf27a9ae51a1476ae7e4df2e3455d2538be3fd16..9725aa0eb54b2641bd572796ced4b8d2b1888679 100644
--- a/src/debug/mirrors.js
+++ b/src/debug/mirrors.js
@@ -13,6 +13,7 @@ var FunctionSourceString;
 var GlobalArray = global.Array;
 var IsNaN = global.isNaN;
 var JSONStringify = global.JSON.stringify;
+var MakeError;
 var MapEntries;
 var MapIteratorNext;
 var MathMin = global.Math.min;
@@ -25,6 +26,7 @@ var SymbolToString;
 utils.Import(function(from) {
   ErrorToString = from.ErrorToString;
   FunctionSourceString = from.FunctionSourceString;
+  MakeError = from.MakeError;
   MapEntries = from.MapEntries;
   MapIteratorNext = from.MapIteratorNext;
   SetIteratorNext = from.SetIteratorNext;