. Optimize the code
. Fixed the bug : when DOM changed or the tooltip DOM element width/height changed,recalculate the tooltip position.

Signed-off-by: jssoscar
Version: 2.0.1
Date: 2014-4-21 15:42:23
Changelog: . Optimize the code
	   . Fixed the bug : when DOM changed or the tooltip DOM element width/height changed,recalculate the tooltip position.