Clean up mark-compact phases and GC counter names.

tools/gc_nvp_common.py

 # Copyright 2015 the V8 project authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 #
 # Common code for parsing --trace-gc-nvp output.
 #
 
 
 from __future__ import with_statement
 import re
 
 def split_nvp(s):
   t = {}
-  for (name, value) in re.findall(r"(\w+)=([-\w]+(?:\.[0-9]+)?)", s):
+  for (name, value) in re.findall(r"([._\w]+)=([-\w]+(?:\.[0-9]+)?)", s):
     try:
       t[name] = float(value)
     except ValueError:
       t[name] = value
 
   return t
 
 
 def parse_gc_trace(input):
   trace = []
   with open(input) as f:
     for line in f:
       info = split_nvp(line)
       if info and 'pause' in info and info['pause'] > 0:
         info['i'] = len(trace)
         trace.append(info)
   return trace