Check for duplicate library names

lib/runtime/dart/_interceptors.js

-var _interceptors = dart.defineLibrary(_interceptors, {});
-var core = dart.import(core);
-var _internal = dart.import(_internal);
-var _js_helper = dart.lazyImport(_js_helper);
-var collection = dart.import(collection);
-var math = dart.import(math);
-(function(exports, core, _internal, _js_helper, collection, math) {
+dart.library('dart/_interceptors.js', null, /* Imports */[
+  'dart/core.js',
+  'dart/_internal.js',
+  'dart/collection.js',
+  'dart/math.js'
+], /* Lazy imports */[
+  'dart/_js_helper.js'
+], function(exports, core, _internal, collection, math, _js_helper) {
   'use strict';
   let JSArray$ = dart.generic(function(E) {
     class JSArray extends core.Object {
       JSArray() {
       }
       static typed(allocation) {
         return dart.list(allocation, E);
       }
       static markFixed(allocation) {
         return JSArray$(E).typed(JSArray$().markFixedList(dart.as(allocation, core.List)));
@@ skipping 1410 matching lines @@
   exports.JSUInt31 = JSUInt31;
   exports.JSString = JSString;
   exports.getInterceptor = getInterceptor;
   exports.JSBool = JSBool;
   exports.JSIndexable = JSIndexable;
   exports.JSMutableIndexable = JSMutableIndexable;
   exports.JSObject = JSObject;
   exports.JavaScriptObject = JavaScriptObject;
   exports.PlainJavaScriptObject = PlainJavaScriptObject;
   exports.UnknownJavaScriptObject = UnknownJavaScriptObject;
-})(_interceptors, core, _internal, _js_helper, collection, math);
+});