[es6] support rest parameters in arrow functions (alternative)

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 3246dfa8e4cd0114e8664a03269da6fb01d2e88b..889937ff86d933fc640a277e9d818622f187cdd0 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -11037,6 +11037,11 @@ void HOptimizedGraphBuilder::HandleLiteralCompareNil(CompareOperation* expr,
 }
 
 
+void HOptimizedGraphBuilder::VisitSpread(Spread* 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.