Requite the keyowrd 'val' in the extended attribute syntax

git-svn-id: http://lampsvn.epfl.ch/svn-repos/scala/scala/trunk@7857 5e8d7ff9-d8ef-0310-90f0-a4852d11357a

src/compiler/scala/tools/nsc/ast/parser/Parsers.scala

@@ -1792,6 +1792,7 @@ trait Parsers requires SyntaxAnalyzer {
      */
     def attribute(): Tree = {
       def nameValuePair(): Tree = {
+        accept(VAL);
         var pos = in.currentPos;
         val aname = atPos(pos) { Ident(ident()) }
         accept(EQUALS);