shadow-dom: Update a test for shadow root's accessors.

Tests in the original file, test-006.html, are rewritten and are now in
two new files: dom-tree-accessors-002.html and selectors-api-002.html.
Merge pull request #237 from yutak/shadow-dom/shadow-root-accessors

shadow-dom: Update a test for shadow root's accessors.
sync with DOM
Merge pull request #244 from annevk/patch-2

sync with DOM
Add a test for empty names in HTMLCollection in DOM.
Add more whitespace between tests.
Merge pull request #245 from Ms2ger/HTMLCollection-empty-name

Add a test for empty names in HTMLCollection in DOM.
whitespace
add OfflineAudioContext to vender prefix
file rename
gain node test