[es6] Fix tail call elimination in single-expression arrow functions.

src/parsing/preparser.h

Index: src/parsing/preparser.h
diff --git a/src/parsing/preparser.h b/src/parsing/preparser.h
index 07375294aa91deeab73c15095c4ce186b8406589..72a73dfa963ac85e460309ec257c9265c5040e84 100644
--- a/src/parsing/preparser.h
+++ b/src/parsing/preparser.h
@@ -887,6 +887,8 @@ class PreParserTraits {
                                         bool name_is_strict_reserved, int pos,
                                         bool* ok);
 
+  V8_INLINE void MarkExpressionInTailPosition(PreParserExpression) {}
+
   PreParserExpressionList PrepareSpreadArguments(PreParserExpressionList list) {
     return list;
   }