Tools gdb script renamed class xrange to range for python3.0

Updated gdb script to use range instead of range.

R=hayato, jochen
BUG=380618

Review URL: https://codereview.chromium.org/313833003

git-svn-id: svn://svn.chromium.org/blink/trunk@175643 bbb929c8-8fbe-4397-9dbb-9b2b20218538