fixes #157, renaming local library identifiers if needed.

test/codegen/expect/8invalid-chars.in+file_name.js

Index: test/codegen/expect/8invalid-chars.in+file_name.js
diff --git a/test/codegen/expect/8invalid-chars.in+file_name.js b/test/codegen/expect/8invalid-chars.in+file_name.js
index fd8aa1174001b82f980c89da847ec1165718dc93..f3537579fc9f427812cc27b2e0da78f171fb4a12 100644
--- a/test/codegen/expect/8invalid-chars.in+file_name.js
+++ b/test/codegen/expect/8invalid-chars.in+file_name.js
@@ -1,4 +1,4 @@
-var $8invalid$45chars$46in$43file_name;
+var $8invalid$45chars$46in$43file_name = dart.defineLibrary($8invalid$45chars$46in$43file_name, {});
 (function(exports) {
   'use strict';
   // Function main: () → dynamic
@@ -6,4 +6,4 @@ var $8invalid$45chars$46in$43file_name;
   }
   // Exports:
   exports.main = main;
-})($8invalid$45chars$46in$43file_name || ($8invalid$45chars$46in$43file_name = {}));
+})($8invalid$45chars$46in$43file_name);