Add experimental support for tracing the state of the VM heap to a file

src/flag-definitions.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 246 matching lines @@
 DEFINE_bool(trace_fragmentation, false,
             "report fragmentation for old pointer and data pages")
 DEFINE_bool(collect_maps, true,
             "garbage collect maps from which no objects can be reached")
 DEFINE_bool(flush_code, false,
             "flush code that we expect not to use again before full gc")
 DEFINE_bool(incremental_marking, true, "use incremental marking")
 DEFINE_bool(incremental_marking_steps, true, "do incremental marking steps")
 DEFINE_bool(trace_incremental_marking, false,
             "trace progress of the incremental marking")
+DEFINE_bool(trace_heap, false, "write a visualization of the heap to a file (d8)")
+DEFINE_string(trace_heap_file, "v8heapvisualization.log",
+              "file name for visualization of the heap (d8)")
 
 // v8.cc
 DEFINE_bool(use_idle_notification, true,
             "Use idle notification to reduce memory footprint.")
 // ic.cc
 DEFINE_bool(use_ic, true, "use inline caching")
 
 #ifdef LIVE_OBJECT_LIST
 // liveobjectlist.cc
 DEFINE_string(lol_workdir, NULL, "path for lol temp files")
@@ skipping 261 matching lines @@
 #undef FLAG
 
 #undef DEFINE_bool
 #undef DEFINE_int
 #undef DEFINE_string
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META