Remove thirdparty/unittest2 from webkitpy and require python2.7.

Tools/Scripts/webkitpy/thirdparty/unittest2/compatibility.py

-import os
-import sys
-
-try:
-    from functools import wraps
-except ImportError:
-    # only needed for Python 2.4
-    def wraps(_):
-        def _wraps(func):
-            return func
-        return _wraps
-
-__unittest = True
-
-def _relpath_nt(path, start=os.path.curdir):
-    """Return a relative version of a path"""
-
-    if not path:
-        raise ValueError("no path specified")
-    start_list = os.path.abspath(start).split(os.path.sep)
-    path_list = os.path.abspath(path).split(os.path.sep)
-    if start_list[0].lower() != path_list[0].lower():
-        unc_path, rest = os.path.splitunc(path)
-        unc_start, rest = os.path.splitunc(start)
-        if bool(unc_path) ^ bool(unc_start):
-            raise ValueError("Cannot mix UNC and non-UNC paths (%s and %s)"
-                                                                % (path, start))
-        else:
-            raise ValueError("path is on drive %s, start on drive %s"
-                                                % (path_list[0], start_list[0]))
-    # Work out how much of the filepath is shared by start and path.
-    for i in range(min(len(start_list), len(path_list))):
-        if start_list[i].lower() != path_list[i].lower():
-            break
-    else:
-        i += 1
-
-    rel_list = [os.path.pardir] * (len(start_list)-i) + path_list[i:]
-    if not rel_list:
-        return os.path.curdir
-    return os.path.join(*rel_list)
-
-# default to posixpath definition
-def _relpath_posix(path, start=os.path.curdir):
-    """Return a relative version of a path"""
-
-    if not path:
-        raise ValueError("no path specified")
-
-    start_list = os.path.abspath(start).split(os.path.sep)
-    path_list = os.path.abspath(path).split(os.path.sep)
-
-    # Work out how much of the filepath is shared by start and path.
-    i = len(os.path.commonprefix([start_list, path_list]))
-
-    rel_list = [os.path.pardir] * (len(start_list)-i) + path_list[i:]
-    if not rel_list:
-        return os.path.curdir
-    return os.path.join(*rel_list)
-
-if os.path is sys.modules.get('ntpath'):
-    relpath = _relpath_nt
-else:
-    relpath = _relpath_posix