Re: [css-rhythm-1-tests] Fix line-height-step-valign-001 (#5251)

@foolip: Both job logs show several errors (shown below). I'm not familiar with these areas of code and have to run to a meeting, so I'll ping @jgraham to see if he has any ideas. If he can't get to it, I'll take a look when I get back.

### Firefox
```
 File "/home/travis/virtualenv/python2.7.12/lib/python2.7/site-packages/wptrunner/executors/pytestrunner/__init__.py", line 5, in <module>

    from . import fixtures

ImportError: cannot import name fixtures
```

```
 File "/home/travis/build/w3c/web-platform-tests/XMLHttpRequest/resources/auth2/corsenabled.py", line 10, in main

    auth = imp.load_source("", os.path.abspath("XMLHttpRequest/resources/authentication.py"))

IOError: [Errno 2] No such file or directory
```

### Chrome
```
  File "/home/travis/virtualenv/python2.7.12/lib/python2.7/site-packages/wptrunner/browsers/chrome.py", line 78, in stop

    self.server.stop(force=Force)

NameError: global name 'Force' is not defined
```

```
  File "/home/travis/build/w3c/web-platform-tests/XMLHttpRequest/resources/auth2/corsenabled.py", line 10, in main

    auth = imp.load_source("", os.path.abspath("XMLHttpRequest/resources/authentication.py"))

IOError: [Errno 2] No such file or directory
```

View on GitHub: https://github.com/w3c/web-platform-tests/pull/5251#issuecomment-292151214

Received on Thursday, 6 April 2017 11:56:34 UTC