Remove support for the DeferredLibrary annotation and remove tests of it

sdk/lib/_internal/lib/js_helper.dart

Index: sdk/lib/_internal/lib/js_helper.dart
diff --git a/sdk/lib/_internal/lib/js_helper.dart b/sdk/lib/_internal/lib/js_helper.dart
index bd1513697f175ea84a08ed0aa79aac2e3733c375..b01292de74147c8c7952edf341bb866c504ea083 100644
--- a/sdk/lib/_internal/lib/js_helper.dart
+++ b/sdk/lib/_internal/lib/js_helper.dart
@@ -3231,19 +3231,19 @@ LoadLibraryFunctionType _loadLibraryWrapper(String loadId) {
 final Map<String, Future<Null>> _loadingLibraries = <String, Future<Null>>{};
 final Set<String> _loadedLibraries = new Set<String>();
 
-Future<Null> loadDeferredLibrary(String loadId, [String uri]) {
+Future<Null> loadDeferredLibrary(String loadId) {
   List<List<String>> hunkLists = JS('JSExtendableArray|Null',
       '\$.libraries_to_load[#]', loadId);
   if (hunkLists == null) return new Future.value(null);
 
   return Future.forEach(hunkLists, (hunkNames) {
     Iterable<Future<Null>> allLoads =
-        hunkNames.map((hunkName) => _loadHunk(hunkName, uri));
+        hunkNames.map((hunkName) => _loadHunk(hunkName));
     return Future.wait(allLoads).then((_) => null);
   }).then((_) => _loadedLibraries.add(loadId));
 }
 
-Future<Null> _loadHunk(String hunkName, String uri) {
+Future<Null> _loadHunk(String hunkName) {
   // TODO(ahe): Validate libraryName.  Kasper points out that you want
   // to be able to experiment with the effect of toggling @DeferLoad,
   // so perhaps we should silently ignore "bad" library names.
@@ -3252,9 +3252,8 @@ Future<Null> _loadHunk(String hunkName, String uri) {
     return future.then((_) => null);
   }
 
-  if (uri == null) {
-    uri = IsolateNatives.thisScript;
-  }
+  String uri = IsolateNatives.thisScript;
+
   int index = uri.lastIndexOf('/');
   uri = '${uri.substring(0, index + 1)}$hunkName';