Land 'Fix a crash related to obsolete factory syntax.'.

lib/compiler/implementation/scanner/class_element_parser.dart

Index: lib/compiler/implementation/scanner/class_element_parser.dart
diff --git a/lib/compiler/implementation/scanner/class_element_parser.dart b/lib/compiler/implementation/scanner/class_element_parser.dart
index b2a4b031eceba4d9d4c0f58377cae3c63a095482..cd1ae549dec3670bb7a6de90a1cee0b044be7f26 100644
--- a/lib/compiler/implementation/scanner/class_element_parser.dart
+++ b/lib/compiler/implementation/scanner/class_element_parser.dart
@@ -99,6 +99,10 @@ class MemberListener extends NodeListener {
       bool isUnary = operator.token.next.next.stringValue === ')';
       return Elements.constructOperatorName(operator.source, isUnary);
     } else {
+      if (receiver == null) {
+        listener.cancel('library prefix in named factory constructor not '
+                        'implemented', node: send.receiver);
+      }
       return Elements.constructConstructorName(receiver.source,
                                                selector.source);
     }