Bug 1627632 [wpt PR 22714] - Python 3: Improve webdriver tests compatibility with...

Bug 1627632 [wpt PR 22714] - Python 3: Improve webdriver tests compatibility with Python 3, a=testonly

Automatic update from web-platform-tests
Python 3: Improve webdriver tests compatibility with Python 3 (#22714)

- Change urlparse, httplib imports to work with both 2.x and 3.x.
- Replace uses of basestring with six library calls.
- Ensure parameter for base64.decodestring() is a byte-like object.
- Convert map to list. In Python 3, map returns an iterator.
- Use six.integer_types for Possible integer types. In Python 2,
  this is long and int, and in Python 3, just int. PEP 237 specifies
  unifying Long Integers and Integers. Essentially, there is only
  one built-in integral type. In Python 3, all integers are implemented
  as “long” integer objects of arbitrary size.
- Use explicit relative imports.
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wpt-commits: f2e918abb4b8711afb28c8b98d98be3bffc9fa9a
wpt-pr: 22714