Fix a crash related to obsolete factory syntax.

dart/lib/compiler/implementation/scanner/class_element_parser.dart

Index: dart/lib/compiler/implementation/scanner/class_element_parser.dart
diff --git a/dart/lib/compiler/implementation/scanner/class_element_parser.dart b/dart/lib/compiler/implementation/scanner/class_element_parser.dart
index b2a4b031eceba4d9d4c0f58377cae3c63a095482..8251eb08d1211f30fbd5cdd72c78bd33de82c34d 100644
--- a/dart/lib/compiler/implementation/scanner/class_element_parser.dart
+++ b/dart/lib/compiler/implementation/scanner/class_element_parser.dart
@@ -99,6 +99,9 @@ class MemberListener extends NodeListener {
       bool isUnary = operator.token.next.next.stringValue === ')';
       return Elements.constructOperatorName(operator.source, isUnary);
     } else {
+      if (receiver == null) {

[Lasse Reichstein Nielsen, 2012/10/15 08:34:37]

What is it that isn't implemented? 

[ahe, 2012/10/15 20:39:15]

Library prefixes in factory names. The error message will highlight the prefix,
so I think the error message is good enough for now (this method will be removed
ASAP).

+        listener.cancel('not implemented', node: send.receiver);
+      }
       return Elements.constructConstructorName(receiver.source,
                                                selector.source);
     }