Force pretenuring of closures that are immediately assigned to...

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
===================================================================
--- src/x64/full-codegen-x64.cc	(revision 5865)
+++ src/x64/full-codegen-x64.cc	(working copy)
@@ -837,17 +837,21 @@
 }
 
 
-void FullCodeGenerator::EmitNewClosure(Handle<SharedFunctionInfo> info) {
+void FullCodeGenerator::EmitNewClosure(Handle<SharedFunctionInfo> info,
+                                       bool pretenure) {
   // Use the fast case closure allocation code that allocates in new
   // space for nested functions that don't need literals cloning.
-  if (scope()->is_function_scope() && info->num_literals() == 0) {
+  if (scope()->is_function_scope() &&
+      info->num_literals() == 0 &&
+      !pretenure) {
     FastNewClosureStub stub;
     __ Push(info);
     __ CallStub(&stub);
   } else {
     __ push(rsi);
     __ Push(info);
-    __ CallRuntime(Runtime::kNewClosure, 2);
+    __ Push(pretenure ? Factory::true_value() : Factory::false_value());
+    __ CallRuntime(Runtime::kNewClosure, 3);
   }
   context()->Plug(rax);
 }