Parse arrow functions at proper precedence level

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 65906573d8ad0505de1c1ce8de30bf5682f12518..3787fdfac648be85fc3cbc70c65ed12d58ca957c 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -11533,6 +11533,11 @@ void HOptimizedGraphBuilder::HandleLiteralCompareNil(CompareOperation* expr,
 void HOptimizedGraphBuilder::VisitSpread(Spread* expr) { UNREACHABLE(); }
 
 
+void HOptimizedGraphBuilder::VisitEmptyParentheses(EmptyParentheses* expr) {
+  UNREACHABLE();
+}
+
+
 HInstruction* HOptimizedGraphBuilder::BuildThisFunction() {
   // If we share optimized code between different closures, the
   // this-function is not a constant, except inside an inlined body.