RemoveText() fails to remove text in some cases
before mPreviousNumberOfCharacters of mTextUpdateInfo is updated.
In all text remove situation, it can be removed regardless of the update of this info.
It's same as the previous preedit all remove behavior.
Change-Id: I7c64a133e6d0df84829dc35c25b71f100da6d702
Signed-off-by: Bowon Ryu <bowon.ryu@samsung.com>