Use NeedsContext() instead of comparing num_heap_slots().

src/full-codegen/s390/full-codegen-s390.cc

Index: src/full-codegen/s390/full-codegen-s390.cc
diff --git a/src/full-codegen/s390/full-codegen-s390.cc b/src/full-codegen/s390/full-codegen-s390.cc
index a07c48da941045bc964aafce06e135b0ef4594a6..b711ce51f4f8def51bec5d13fae08e980819bd0f 100644
--- a/src/full-codegen/s390/full-codegen-s390.cc
+++ b/src/full-codegen/s390/full-codegen-s390.cc
@@ -178,7 +178,7 @@ void FullCodeGenerator::Generate() {
   bool function_in_register_r3 = true;
 
   // Possibly allocate a local context.
-  if (info->scope()->num_heap_slots() > 0) {
+  if (info->scope()->NeedsContext()) {
     // Argument to NewContext is the function, which is still in r3.
     Comment cmnt(masm_, "[ Allocate context");
     bool need_write_barrier = true;
@@ -1142,7 +1142,7 @@ MemOperand FullCodeGenerator::ContextSlotOperandCheckExtensions(Variable* var,
   Register temp = r6;
 
   for (Scope* s = scope(); s != var->scope(); s = s->outer_scope()) {
-    if (s->num_heap_slots() > 0) {
+    if (s->NeedsContext()) {
       if (s->calls_sloppy_eval()) {
         // Check that extension is "the hole".
         __ LoadP(temp, ContextMemOperand(context, Context::EXTENSION_INDEX));