RingBuffer<T, N> utility with unit test; use for GC history.

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 297 matching lines @@
     'profiler_test.cc',
     'random.cc',
     'random.h',
     'raw_object.cc',
     'raw_object.h',
     'raw_object_snapshot.cc',
     'resolver.cc',
     'resolver.h',
     'resolver_test.cc',
     'reusable_handles.h',
+    'ring_buffer.h',
+    'ring_buffer_test.cc',
     'runtime_entry.h',
     'runtime_entry_arm.cc',
     'runtime_entry_arm64.cc',
     'runtime_entry_ia32.cc',
     'runtime_entry_mips.cc',
     'runtime_entry_test.cc',
     'runtime_entry_x64.cc',
     'scanner.cc',
     'scanner.h',
     'scanner_test.cc',
@@ skipping 86 matching lines @@
     'visitor.h',
     'vtune.cc',
     'vtune.h',
     'weak_table.cc',
     'weak_table.h',
     'zone.cc',
     'zone.h',
     'zone_test.cc',
   ],
 }