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

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

-import signal
-import weakref
-
-from unittest2.compatibility import wraps
-
-__unittest = True
-
-
-class _InterruptHandler(object):
-    def __init__(self, default_handler):
-        self.called = False
-        self.default_handler = default_handler
-
-    def __call__(self, signum, frame):
-        installed_handler = signal.getsignal(signal.SIGINT)
-        if installed_handler is not self:
-            # if we aren't the installed handler, then delegate immediately
-            # to the default handler
-            self.default_handler(signum, frame)
-
-        if self.called:
-            self.default_handler(signum, frame)
-        self.called = True
-        for result in _results.keys():
-            result.stop()
-
-_results = weakref.WeakKeyDictionary()
-def registerResult(result):
-    _results[result] = 1
-
-def removeResult(result):
-    return bool(_results.pop(result, None))
-
-_interrupt_handler = None
-def installHandler():
-    global _interrupt_handler
-    if _interrupt_handler is None:
-        default_handler = signal.getsignal(signal.SIGINT)
-        _interrupt_handler = _InterruptHandler(default_handler)
-        signal.signal(signal.SIGINT, _interrupt_handler)
-
-
-def removeHandler(method=None):
-    if method is not None:
-        @wraps(method)
-        def inner(*args, **kwargs):
-            initial = signal.getsignal(signal.SIGINT)
-            removeHandler()
-            try:
-                return method(*args, **kwargs)
-            finally:
-                signal.signal(signal.SIGINT, initial)
-        return inner
-
-    global _interrupt_handler
-    if _interrupt_handler is not None:
-        signal.signal(signal.SIGINT, _interrupt_handler.default_handler)