gn docs generator: Don't get confused by ansi escape codes.

BUG=362239
TEST=links at the top of the output actually work.
NOTRY=true

Review URL: https://codereview.chromium.org/232703004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@263087 0039d316-1c4b-4281-b951-d872f2087c98

tools/gn/bin/help_as_html.py

@@ -12,13 +12,17 @@
 # - Spit out other similar formats like wiki, markdown, whatever.
 
 import cgi
+import re
 import subprocess
 import sys
 
 
 def GetOutput(*args):
   try:
-    return subprocess.check_output([sys.argv[1]] + list(args))
+    # TODO: Remove ansi escape code stripping if crbug.com/362239 gets fixed.
+    ansi_escape = re.compile(r'\x1b[^m]*m')
+    return ansi_escape.sub(
+        '', subprocess.check_output([sys.argv[1]] + list(args)))
   except subprocess.CalledProcessError:
     return ''