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

runtime/vm/debugger_api_impl.cc

Index: runtime/vm/debugger_api_impl.cc
diff --git a/runtime/vm/debugger_api_impl.cc b/runtime/vm/debugger_api_impl.cc
index 71610d2b096025e2f749f6df3df5575957372335..77b7b272fc41deb42112c1418d8f156d5b566362 100644
--- a/runtime/vm/debugger_api_impl.cc
+++ b/runtime/vm/debugger_api_impl.cc
@@ -485,7 +485,7 @@ DART_EXPORT Dart_Handle Dart_SetStepOver() {
   DARTSCOPE(Thread::Current());
   Isolate* I = T->isolate();
   CHECK_DEBUGGER(I);
-  I->debugger()->SetStepOver();
+  I->debugger()->SetResumeAction(Debugger::kStepOver);
   return Api::Success();
 }
 
@@ -494,7 +494,7 @@ DART_EXPORT Dart_Handle Dart_SetStepInto() {
   DARTSCOPE(Thread::Current());
   Isolate* I = T->isolate();
   CHECK_DEBUGGER(I);
-  I->debugger()->SetSingleStep();
+  I->debugger()->SetResumeAction(Debugger::kStepInto);
   return Api::Success();
 }
 
@@ -503,7 +503,7 @@ DART_EXPORT Dart_Handle Dart_SetStepOut() {
   DARTSCOPE(Thread::Current());
   Isolate* I = T->isolate();
   CHECK_DEBUGGER(I);
-  I->debugger()->SetStepOut();
+  I->debugger()->SetResumeAction(Debugger::kStepOut);
   return Api::Success();
 }