Check for duplicate library names

lib/runtime/dart/convert.js

-var convert = dart.defineLibrary(convert, {});
-var core = dart.import(core);
-var async = dart.import(async);
-var typed_data = dart.import(typed_data);
-var _internal = dart.import(_internal);
-var collection = dart.import(collection);
-(function(exports, core, async, typed_data, _internal, collection) {
+dart.library('dart/convert', null, /* Imports */[
+  'dart/core',
+  'dart/async',
+  'dart/typed_data',
+  'dart/_internal',
+  'dart/collection'
+], /* Lazy imports */[
+], function(exports, core, async, typed_data, _internal, collection) {
   'use strict';
   let Codec$ = dart.generic(function(S, T) {
     class Codec extends core.Object {
       Codec() {
       }
       encode(input) {
         dart.as(input, S);
         return this.encoder.convert(input);
       }
       decode(encoded) {
@@ skipping 2871 matching lines @@
   exports.Latin1Decoder = Latin1Decoder;
   exports.LineSplitter = LineSplitter;
   exports.StringConversionSink = StringConversionSink;
   exports.ClosableStringSink = ClosableStringSink;
   exports.UNICODE_REPLACEMENT_CHARACTER_RUNE = UNICODE_REPLACEMENT_CHARACTER_RUNE;
   exports.UNICODE_BOM_CHARACTER_RUNE = UNICODE_BOM_CHARACTER_RUNE;
   exports.Utf8Codec = Utf8Codec;
   exports.UTF8 = UTF8;
   exports.Utf8Encoder = Utf8Encoder;
   exports.Utf8Decoder = Utf8Decoder;
-})(convert, core, async, typed_data, _internal, collection);
+});