Support all 8 dots for braille keyboard input.

Add tests for all keyboard commands currently recognized.

BUG=310285
R=dtseng@chromium.org

Review URL: https://codereview.chromium.org/145813008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251600 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251600