[debugger] flood function for stepping before calling it.

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..31e87c2efbe469bb56fff46063238c3cfdcac12f 100644
--- a/src/runtime/runtime-debug.cc
+++ b/src/runtime/runtime-debug.cc
@@ -1658,25 +1658,15 @@ RUNTIME_FUNCTION(Runtime_DebugCallbackSupportsStepping) {
 }
 
 
-void FloodDebugSubjectWithOneShot(Debug* debug, Handle<JSFunction> function) {
-  if (function->shared()->IsSubjectToDebugging() ||
-      function->shared()->bound()) {
-    // When leaving the function, step out has been activated, but not performed
-    // if we do not leave the builtin.  To be able to step into the function
-    // again, we need to clear the step out at this point.
-    debug->ClearStepOut();
-    debug->FloodWithOneShotGeneric(function);
-  }
-}
-
-
 // Set one shot breakpoints for the callback function that is passed to a
 // built-in function such as Array.forEach to enable stepping into the callback,
 // if we are indeed stepping and the callback is subject to debugging.
 RUNTIME_FUNCTION(Runtime_DebugPrepareStepInIfStepping) {
   DCHECK(args.length() == 1);
   Debug* debug = isolate->debug();
-  if (!DebugStepInIsActive(debug)) return isolate->heap()->undefined_value();
+  if (debug->in_debug_scope() || !DebugStepInIsActive(debug)) {
+    return isolate->heap()->undefined_value();
+  }
 
   HandleScope scope(isolate);
   CONVERT_ARG_HANDLE_CHECKED(Object, object, 0);
@@ -1689,22 +1679,18 @@ RUNTIME_FUNCTION(Runtime_DebugPrepareStepInIfStepping) {
         Handle<JSGeneratorObject>::cast(object)->function(), isolate);
   }
 
-  FloodDebugSubjectWithOneShot(debug, fun);
+  debug->ClearStepOut();
+  debug->FloodWithOneShotGeneric(fun);
   return isolate->heap()->undefined_value();
 }
 
 
 RUNTIME_FUNCTION(Runtime_DebugPushPromise) {
-  DCHECK(args.length() == 3);
+  DCHECK(args.length() == 2);
   HandleScope scope(isolate);
   CONVERT_ARG_HANDLE_CHECKED(JSObject, promise, 0);
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, function, 1);
-  CONVERT_ARG_HANDLE_CHECKED(Object, handler, 2);
   isolate->PushPromise(promise, function);
-  Debug* debug = isolate->debug();
-  if (handler->IsJSFunction() && DebugStepInIsActive(debug)) {
-    FloodDebugSubjectWithOneShot(debug, Handle<JSFunction>::cast(handler));
-  }
   return isolate->heap()->undefined_value();
 }