Make --always-opt also optimize toplevel code.

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 18b230539b1afc193841f3c9fdb588b77f6d6352..6750510397f6db59992e71bcfe53faa4a8bb74a7 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -193,7 +193,11 @@ bool LCodeGen::GeneratePrologue() {
     Comment(";;; Allocate local context");
     bool need_write_barrier = true;
     // Argument to NewContext is the function, which is still in rdi.
-    if (heap_slots <= FastNewContextStub::kMaximumSlots) {
+    if (FLAG_harmony_scoping && info()->scope()->is_global_scope()) {
+      __ Push(rdi);
+      __ Push(info()->scope()->GetScopeInfo());
+      __ CallRuntime(Runtime::kNewGlobalContext, 2);
+    } else if (heap_slots <= FastNewContextStub::kMaximumSlots) {
       FastNewContextStub stub(isolate(), heap_slots);
       __ CallStub(&stub);
       // Result of FastNewContextStub is always in new space.