shadow-dom: Remove .gitattributes.

This change removes the .gitattributes file, based on the discussion at
<https://github.com/w3c/web-platform-tests/pull/120>.
Merge pull request #129 from yutak/shadow-dom/remove-gitattributes

shadow-dom: Remove .gitattributes.
Fix typo.
shadow-dom: Add test conversion script.

This script converts tests under the shadow-dom/ directory to separate HTML
files with appropriate metadata format. The output is produced within
the out/ directory by default to avoid conflicts with existing files, but
I intend that the files under the out/ directory will take over the existing
contents of the shadow-dom/ directory.

The script file will be removed after the conversion.
shadow-dom: Reorganize the test structure.

This change reorganizes the tests under the shadow-dom/ directory. In the new
format, each test has a dedicated, clean HTML with appropriate metadata.
The new format provides a clear directory structure based on the section
hierarchy of the specification. In addition, numerous issues with the existing
tests are addressed, such as unnecessary files, messy metadata definitions,
and so on.

The new files are generated by convert.py, which is included in the previous
commit.

There are some issues I could not address using a script; most notably
each test does not have a sensible name. These issues need to be addressed
manually, so I left these as future work.
shadow-dom: Remove convert.py.
Merge pull request #130 from yutak/shadow-dom/convert-tests

shadow-dom: Reorganize the test structure
Make blink an HTMLUnknownElement.
http://html5.org/tools/web-apps-tracker?from=7904&to=7905
Merge pull request #132 from Ms2ger/blink-interface

Make blink an HTMLUnknownElement.
shadow-dom: Drop section numbers from directory names.

This change is based on the discussion at
<https://github.com/w3c/web-platform-tests/pull/130>.

There is no change in test contents.
Merge pull request #134 from yutak/shadow-dom/drop-section-numbers

shadow-dom: Drop section numbers from directory names.
updated README.md to make it somewhat closer to what the repo really is nowadays