[tools] Fix regexp grepping for GC NVP float values.

R=ulan@chromium.org

Review URL: https://codereview.chromium.org/1422543005

Cr-Commit-Position: refs/heads/master@{#31448}

tools/gc_nvp_common.py

@@ -12,7 +12,7 @@ import re
 
 def split_nvp(s):
   t = {}
-  for (name, value) in re.findall(r"(\w+)=([-\w]+)", s):
+  for (name, value) in re.findall(r"(\w+)=([-\w]+(?:\.[0-9]+)?)", s):
     try:
       t[name] = float(value)
     except ValueError: