[dart2dart] Force-compile top-level elements in libraries to get local members correctly.

lib/compiler/implementation/dart_backend/backend.dart

Index: lib/compiler/implementation/dart_backend/backend.dart
diff --git a/lib/compiler/implementation/dart_backend/backend.dart b/lib/compiler/implementation/dart_backend/backend.dart
index 41bf6e975620d1f44f96f004318533d54e04575a..3f8ed70ce27dabf7ef29a76c360af150f6d3c7b6 100644
--- a/lib/compiler/implementation/dart_backend/backend.dart
+++ b/lib/compiler/implementation/dart_backend/backend.dart
@@ -218,6 +218,10 @@ class DartBackend extends Backend {
       for (final element in library.localMembers) {
         if (element is ClassElement) {
           ClassElement classElement = element;
+          // Make sure we parsed the class to initialize its local members.
+          // TODO(smok): Figure out if there is a better way to fill local
+          // members.
+          element.parseNode(compiler);
           for (final member in classElement.localMembers) {
             final name = member.name.slowToString();
             // Skip operator names.