Enable preaging of code objects when --optimize-for-size.

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 e224fba9b67d833e9c93eda7edbd424756660de3..23ff9be5a120852469d95a8dc58d9236b05e858c 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -166,7 +166,15 @@ bool LCodeGen::GeneratePrologue() {
     frame_is_built_ = true;
     __ push(rbp);  // Caller's frame pointer.
     __ movq(rbp, rsp);
-    __ push(rsi);  // Callee's context.
+    if (isolate()->is_memory_constrained()) {
+      // This sequence marks pre-aged code.
+      __ push(rsi);  // Callee's context.
+      __ nop();
+    } else {
+      // This sequence marks non-aged code.
+      __ nop();
+      __ push(rsi);  // Callee's context
+    }
     if (info()->IsStub()) {
       __ Push(Smi::FromInt(StackFrame::STUB));
     } else {