Set the text bgcolor only when CursorAnchorInfo is available

When CursorAnchorInfo is unavailable, we shouldn't try to show
the commit indicator and set the text highlight color.

With this CL, RichInputConnection can be used to track if the
application responded that it does support CursorAnchorInfo or
not.  This result will be taken into consideration when
InputLogic needs to determine whether the commit indicator
should be displayed or not.

Change-Id: I945d70eeb02a7a5f3d9b22459b23d7028508910f