Record default clause for interfaces in parser.

lib/compiler/implementation/dart_backend/emitter.dart

Index: lib/compiler/implementation/dart_backend/emitter.dart
diff --git a/lib/compiler/implementation/dart_backend/emitter.dart b/lib/compiler/implementation/dart_backend/emitter.dart
index 71b670b434150f5e34129413be7915c702d56d38..1232e189da07d8b0e04fac225067b61d7fdd5599 100644
--- a/lib/compiler/implementation/dart_backend/emitter.dart
+++ b/lib/compiler/implementation/dart_backend/emitter.dart
@@ -21,6 +21,14 @@ class Emitter {
     sb.add(classElement.beginToken.slowToString());  // 'class' or 'interface'.
     sb.add(' ');
     sb.add(classElement.name.slowToString());
+    if (classElement.isInterface() && classElement.defaultClause !== null) {
+      sb.add(' default ');
+      sb.add(classElement.defaultClause.unparse());
+    }
+    if (!classElement.interfaces.isEmpty()) {
+      sb.add(' implements ');
+      classElement.interfaces.printOn(sb, ',');
+    }
     sb.add('{');
     innerElements.forEach((element) {
       // TODO(smok): Filter out default constructors here.