Implement rewind: drop one or more frames from the debugger.

runtime/vm/dart_entry.cc

Index: runtime/vm/dart_entry.cc
diff --git a/runtime/vm/dart_entry.cc b/runtime/vm/dart_entry.cc
index 3346befc81d4294ca7696fbb113ed5d1d8bebffd..ae0f13f07138ee8aec12e5f2f54b31ed586d09b3 100644
--- a/runtime/vm/dart_entry.cc
+++ b/runtime/vm/dart_entry.cc
@@ -551,7 +551,7 @@ RawObject* DartLibraryCalls::HandleMessage(const Object& handler,
     // If the isolate is being debugged and the debugger was stepping
     // through code, enable single stepping so debugger will stop
     // at the first location the user is interested in.
-    isolate->debugger()->SetSingleStep();
+    isolate->debugger()->SetResumeAction(Debugger::kStepInto);
   }
   const Object& result =
       Object::Handle(zone, DartEntry::InvokeFunction(function, args));