Check for duplicate library names

test/codegen/expect/dir/html_input_d.js

Index: test/codegen/expect/dir/html_input_d.js
diff --git a/test/codegen/expect/dir/html_input_d.js b/test/codegen/expect/dir/html_input_d.js
index f934b4d0514526e7135239b146ad2a6a6cadd808..d4620a9dc118078a03dbbfecbdd80182e41b6da3 100644
--- a/test/codegen/expect/dir/html_input_d.js
+++ b/test/codegen/expect/dir/html_input_d.js
@@ -1,6 +1,7 @@
-var html_input_d = dart.defineLibrary(html_input_d, {});
-var core = dart.import(core);
-(function(exports, core) {
+dart.library('dir/html_input_d.js', null, /* Imports */[
+  'dart/core.js'
+], /* Lazy imports */[
+], function(exports, core) {
   'use strict';
   function fib(n) {
     return n == 0 || n == 1 ? 1 : dart.notNull(fib(dart.notNull(n) - 1)) + dart.notNull(fib(dart.notNull(n) - 2));
@@ -8,4 +9,4 @@ var core = dart.import(core);
   dart.fn(fib, core.int, [core.int]);
   // Exports:
   exports.fib = fib;
-})(html_input_d, core);
+});