Simplify pushing function argument for context allocation.

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index 1d9b8fffc2ba31442de8df8b9edddc25620ef549..813e5d1f2f427faa7be48f5210b762fc516ef7cc 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -4119,14 +4119,16 @@ void FullCodeGenerator::LoadContextField(Register dst, int context_index) {
 }
 
 
-void FullCodeGenerator::PushFunctionArgumentForContextAllocation() {
+void FullCodeGenerator::PushFunctionArgumentForContextAllocation(
+    Register scratch) {
   Scope* declaration_scope = scope()->DeclarationScope();
   if (declaration_scope->is_global_scope()) {
     // Contexts nested in the global context have a canonical empty function
     // as their closure, not the anonymous closure containing the global
-    // code.  Pass a smi sentinel and let the runtime look up the empty
-    // function.
-    __ Push(Smi::FromInt(0));
+    // code.
+    __ movq(scratch, GlobalObjectOperand());
+    __ movq(scratch, FieldOperand(scratch, GlobalObject::kGlobalContextOffset));
+    __ push(ContextOperand(scratch, Context::CLOSURE_INDEX));
   } else if (declaration_scope->is_eval_scope()) {
     // Contexts created by a call to eval have the same closure as the
     // context calling eval, not the anonymous closure containing the eval