Delete redundant functions for auxiliary text.

This patch unifies:
* IBusPanelCandidateWindowHandlerInterface::UpdateAuxiliaryText into UpdateLookupTable
* InputMethodEngineInterface::SetCandidateWindowAuxText into SetCandidateWindowProperty
* InputMethodEngineInterface::SetCandidateWindowAuxTextVisible into SetCandidateWindowProperty


BUG=N/A

Review URL: https://codereview.chromium.org/111333004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242610 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242610