[debugger] simplify debug stepping.

src/arm64/builtins-arm64.cc

Index: src/arm64/builtins-arm64.cc
diff --git a/src/arm64/builtins-arm64.cc b/src/arm64/builtins-arm64.cc
index 38513fe072f939685e145562373911735f9a0453..425fd6395aadd439278e76c5831dfbfae18c4b45 100644
--- a/src/arm64/builtins-arm64.cc
+++ b/src/arm64/builtins-arm64.cc
@@ -726,11 +726,12 @@ 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(x10, Operand(step_in_enabled));
-  __ Ldrb(x10, MemOperand(x10));
-  __ CompareAndBranch(x10, Operand(0), ne, &prepare_step_in_if_stepping);
+  ExternalReference last_step_action =
+      ExternalReference::debug_last_step_action_address(masm->isolate());
+  STATIC_ASSERT(StepFrame > StepIn);
+  __ Mov(x10, Operand(last_step_action));
+  __ Ldrsb(x10, MemOperand(x10));
+  __ CompareAndBranch(x10, Operand(StepIn), ge, &prepare_step_in_if_stepping);
 
   // Flood function if we need to continue stepping in the suspended generator.
   ExternalReference debug_suspended_generator =