Fix up some unit tests for HostResolver:
Fix up some unit tests for HostResolver:

- When testing IPv4 addresses, use a pass-through
  HostMapper.  The previous version wasn't actually testing
  anything, because there's a default HostMapper which maps
  all unknown inputs to 127.0.0.1

- Make sure bare IPv6 literals can be resolved.  This was
  going to handle [brackets], but we've decided these should
  be stripped at a higher layer.

- Add an empty address test.

The patch is contributed by Paul Marks of Google.
Original review: http://codereview.chromium.org/113026

R=wtc
BUG=N/A
TEST=N/A
Review URL: http://codereview.chromium.org/113066

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@15483 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser