Debug: Allow stepping into on a given call frame.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index d0754609f708ef49769ca799db168d1201e22874..c7528ab2e756019f971bac514372355d5b0ff558 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -12610,8 +12610,11 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_PrepareStep) {
     return isolate->Throw(isolate->heap()->illegal_argument_string());
   }
 
-  if (frame_id != StackFrame::NO_ID && step_action != StepNext &&
-      step_action != StepMin && step_action != StepOut) {
+  if (frame_id != StackFrame::NO_ID &&
+      step_action != StepIn &&
+      step_action != StepNext &&
+      step_action != StepOut &&
+      step_action != StepMin) {
     return isolate->ThrowIllegalOperation();
   }