[debugger] Remove obsolete stepping modes.

src/runtime/runtime-debug.cc

Index: src/runtime/runtime-debug.cc
diff --git a/src/runtime/runtime-debug.cc b/src/runtime/runtime-debug.cc
index 8bdec1061b1f92af06c7938db61fdbe7d9b7c83c..4e180e856ba16ae2db65ca01cc2495bc73976ffb 100644
--- a/src/runtime/runtime-debug.cc
+++ b/src/runtime/runtime-debug.cc
@@ -1232,13 +1232,12 @@ RUNTIME_FUNCTION(Runtime_PrepareStep) {
   // Get the step action and check validity.
   StepAction step_action = static_cast<StepAction>(NumberToInt32(args[1]));
   if (step_action != StepIn && step_action != StepNext &&
-      step_action != StepOut && step_action != StepInMin &&
-      step_action != StepMin && step_action != StepFrame) {
+      step_action != StepOut && step_action != StepFrame) {
     return isolate->Throw(isolate->heap()->illegal_argument_string());
   }
 
   if (frame_id != StackFrame::NO_ID && step_action != StepNext &&
-      step_action != StepMin && step_action != StepOut) {
+      step_action != StepOut) {
     return isolate->ThrowIllegalOperation();
   }