Add gdb helper functions for creating a handle and using ToCString with RawObjects.

runtime/vm/vm_sources.gypi

 # Copyright (c) 2013, 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.
 
 # This file contains all sources (vm and tests) for the dart virtual machine.
 # Unit test files need to have a '_test' suffix appended to the name.
 {
   'sources': [
     'allocation.cc',
     'allocation.h',
@@ skipping 185 matching lines @@
     'flow_graph_range_analysis_test.cc',
     'flow_graph_type_propagator.cc',
     'flow_graph_type_propagator.h',
     'freelist.cc',
     'freelist.h',
     'freelist_test.cc',
     'gc_marker.cc',
     'gc_marker.h',
     'gc_sweeper.cc',
     'gc_sweeper.h',
+    'gdb_helpers.cc',
     'globals.h',
     'growable_array.h',
     'growable_array_test.cc',
     'guard_field_test.cc',
     'handles.cc',
     'handles.h',
     'handles_impl.h',
     'handles_test.cc',
     'hash_map.h',
     'hash_map_test.cc',
@@ skipping 330 matching lines @@
     'weak_code.h',
     'weak_table.cc',
     'weak_table.h',
     'zone.cc',
     'zone.h',
     'zone_test.cc',
     'zone_text_buffer.cc',
     'zone_text_buffer.h',
   ],
 }