Build LIBRARY_ELEMENT after RESOLVED_UNIT6 for all units in the closure of a library.

pkg/analyzer/lib/src/plugin/engine_plugin.dart

Index: pkg/analyzer/lib/src/plugin/engine_plugin.dart
diff --git a/pkg/analyzer/lib/src/plugin/engine_plugin.dart b/pkg/analyzer/lib/src/plugin/engine_plugin.dart
index bed119196c3370f77ce0aad0a345d00eed0d1bcf..769d18f433ae1dc6ba61be5a7d0f348745253f77 100644
--- a/pkg/analyzer/lib/src/plugin/engine_plugin.dart
+++ b/pkg/analyzer/lib/src/plugin/engine_plugin.dart
@@ -83,8 +83,9 @@ class EnginePlugin implements Plugin {
     registerExtension(taskId, LibraryErrorsReadyTask.DESCRIPTOR);
     registerExtension(taskId, LibraryUnitErrorsTask.DESCRIPTOR);
     registerExtension(taskId, ParseDartTask.DESCRIPTOR);
+    registerExtension(taskId, ResolveLibraryReferencesTask.DESCRIPTOR);
     registerExtension(taskId, ResolveLibraryTypeNamesTask.DESCRIPTOR);
-    registerExtension(taskId, ResolveReferencesTask.DESCRIPTOR);
+    registerExtension(taskId, ResolveUnitReferencesTask.DESCRIPTOR);
     registerExtension(taskId, ResolveUnitTypeNamesTask.DESCRIPTOR);
     registerExtension(taskId, ResolveVariableReferencesTask.DESCRIPTOR);
     registerExtension(taskId, ScanDartTask.DESCRIPTOR);