Move error message makers off js builtins object.

src/debug/debug.js

Index: src/debug/debug.js
diff --git a/src/debug/debug.js b/src/debug/debug.js
index 59df880bfaaea29248489fe4d41ace5214d53322..933172c08f778cd1b021b5fab80afb12c55e164d 100644
--- a/src/debug/debug.js
+++ b/src/debug/debug.js
@@ -15,6 +15,8 @@ var IsNaN = global.isNaN;
 var JSONParse = global.JSON.parse;
 var JSONStringify = global.JSON.stringify;
 var LookupMirror = global.LookupMirror;
+var MakeError;
+var MakeTypeError;
 var MakeMirror = global.MakeMirror;
 var MakeMirrorSerializer = global.MakeMirrorSerializer;
 var MathMin = global.Math.min;
@@ -24,6 +26,8 @@ var ParseInt = global.parseInt;
 var ValueMirror = global.ValueMirror;
 
 utils.Import(function(from) {
+  MakeError = from.MakeError;
+  MakeTypeError = from.MakeTypeError;
   MirrorType = from.MirrorType;
 });