[debugger] simplify debug stepping.

src/s390/builtins-s390.cc

Index: src/s390/builtins-s390.cc
diff --git a/src/s390/builtins-s390.cc b/src/s390/builtins-s390.cc
index 625fa9292e8ff480e6c546715adf0c5ada0935e3..7c8b8eeb830092df4878350c8dc673bc47f3f6a6 100644
--- a/src/s390/builtins-s390.cc
+++ b/src/s390/builtins-s390.cc
@@ -710,12 +710,13 @@ void Builtins::Generate_ResumeGeneratorTrampoline(MacroAssembler* masm) {
   // Flood function if we are stepping.
   Label prepare_step_in_if_stepping, prepare_step_in_suspended_generator;
   Label stepping_prepared;
-  ExternalReference step_in_enabled =
-      ExternalReference::debug_step_in_enabled_address(masm->isolate());
-  __ mov(ip, Operand(step_in_enabled));
+  ExternalReference last_step_action =
+      ExternalReference::debug_last_step_action_address(masm->isolate());
+  STATIC_ASSERT(StepFrame > StepIn);
+  __ mov(ip, Operand(last_step_action));
   __ LoadlB(ip, MemOperand(ip));
   __ CmpP(ip, Operand::Zero());
-  __ bne(&prepare_step_in_if_stepping);
+  __ bge(&prepare_step_in_if_stepping);
 
   // Flood function if we need to continue stepping in the suspended generator.