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

runtime/vm/object.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/become.h"
@@ skipping 11684 matching lines @@
     case RawPcDescriptors::kDeopt:
       return "deopt        ";
     case RawPcDescriptors::kIcCall:
       return "ic-call      ";
     case RawPcDescriptors::kUnoptStaticCall:
       return "unopt-call   ";
     case RawPcDescriptors::kRuntimeCall:
       return "runtime-call ";
     case RawPcDescriptors::kOsrEntry:
       return "osr-entry    ";
+    case RawPcDescriptors::kRewind:
+      return "rewind       ";
     case RawPcDescriptors::kOther:
       return "other        ";
     case RawPcDescriptors::kAnyKind:
       UNREACHABLE();
       break;
   }
   UNREACHABLE();
   return "";
 }
 
@@ skipping 11056 matching lines @@
   return UserTag::null();
 }
 
 
 const char* UserTag::ToCString() const {
   const String& tag_label = String::Handle(label());
   return tag_label.ToCString();
 }
 
 }  // namespace dart