Parse arrow functions at proper precedence level

src/ast-numbering.cc

Index: src/ast-numbering.cc
diff --git a/src/ast-numbering.cc b/src/ast-numbering.cc
index dc0528caa0cff687feec0ddb359a1704e7171a53..7338cc6724219678852d5a90c40155b5a62e53ad 100644
--- a/src/ast-numbering.cc
+++ b/src/ast-numbering.cc
@@ -371,6 +371,11 @@ void AstNumberingVisitor::VisitSpread(Spread* node) {
 }
 
 
+void AstNumberingVisitor::VisitEmptyParentheses(EmptyParentheses* node) {
+  UNREACHABLE();
+}
+
+
 void AstNumberingVisitor::VisitForInStatement(ForInStatement* node) {
   IncrementNodeCount();
   DisableSelfOptimization();