Fix issue 571: display descriptive names for code objects from snapshot.

src/log.h

Index: src/log.h
diff --git a/src/log.h b/src/log.h
index 4d5acced692c9ba2701cedbd266b87f2f6bd98c5..e21df033bf6a2d63692ad384aacc1ffc9d420783 100644
--- a/src/log.h
+++ b/src/log.h
@@ -116,6 +116,7 @@ class VMState BASE_EMBEDDED {
   V(CODE_CREATION_EVENT,            "code-creation",          "cc")       \
   V(CODE_MOVE_EVENT,                "code-move",              "cm")       \
   V(CODE_DELETE_EVENT,              "code-delete",            "cd")       \
+  V(SNAPSHOT_POSITION_EVENT,        "snapshot-pos",           "sp")       \
   V(TICK_EVENT,                     "tick",                   "t")        \
   V(REPEAT_META_EVENT,              "repeat",                 "r")        \
   V(BUILTIN_TAG,                    "Builtin",                "bi")       \
@@ -224,6 +225,8 @@ class Logger {
   // Emits a code delete event.
   static void CodeDeleteEvent(Address from);
 
+  static void SnapshotPositionEvent(Address addr, int pos);
+
   // ==== Events logged by --log-gc. ====
   // Heap sampling events: start, end, and individual types.
   static void HeapSampleBeginEvent(const char* space, const char* kind);