Incremental compilation of added class.

dart/pkg/compiler/lib/src/scanner/class_element_parser.dart

Index: dart/pkg/compiler/lib/src/scanner/class_element_parser.dart
diff --git a/dart/pkg/compiler/lib/src/scanner/class_element_parser.dart b/dart/pkg/compiler/lib/src/scanner/class_element_parser.dart
index 6c43527c1404132e7689f7b9acba432bd0b6fe2d..d1fe842c87898958e31ee274e8a033116ecefa8a 100644
--- a/dart/pkg/compiler/lib/src/scanner/class_element_parser.dart
+++ b/dart/pkg/compiler/lib/src/scanner/class_element_parser.dart
@@ -73,6 +73,10 @@ class PartialClassElement extends ClassElementX with PartialElement {
       cachedNode != null ? cachedNode.modifiers : Modifiers.EMPTY;
 
   accept(ElementVisitor visitor) => visitor.visitClassElement(this);
+
+  PartialClassElement copyWithEnclosing(CompilationUnitElement enclosing) {
+    return new PartialClassElement(name, beginToken, endToken, enclosing, id);
+  }
 }
 
 class MemberListener extends NodeListener {