createLink: Make |canUnwrapContents()| to local function of  |unwrapAnchorContents()|.
insertOrderedList: Fix #50, #51, #52
unlink: Implement unwrap of A element.
Fix #10
unlink: Update test expectations to much Chrome's behavior.
editing.nodes: Utilize |Node.prototype.contains()| in |editing.nodes.isDescendantOf()|.
Fix #50, #51, #52 for all files
Merge master
Revert "editing.nodes: Utilize |Node.prototype.contains()| in |editing.nodes.isDescendantOf()|."

This reverts commit 1961e630afd45095b231537199bd85d40427af94.
Because of closure compiler have wrong externs for |Node.prototype.contains()|.
Merge pull request #57 from hajimehoshi/issue-50

insertOrderedList: Fix #50, #51, #52
unlink: Bug fix: replace 'return' with 'continue'
Merge pull request #58 from hajimehoshi/bug-unlink

unlink: Bug fix: replace 'return' with 'continue'