触发、清除 haslayout的css属性

触发haslayout的css属性：

  position:   absolute
  float:      left | right
  display:    inline-block
  width:      except 'auto'
  height:     except 'auto'
  zoom:       except 'normal'
  overflow:   hidden | scroll | auto
  overflow-x/-y: hidden | scroll | auto
  position:   fixed
  min-width:  any value
  max-width:  except 'none'
  min-height: any value
  max-height:  except 'none'
  writing-mode: tb-rl   /* only for MS */
  zoom:1; 

清除hasLayout的css属性：

  width:        auto;
  height:       auto;
  max-width:    none;   /* IE7 */
  max-height:   none;   /* IE7 */
  position:     static;
  float:        none;
  overflow:     visible;
  zoom:         normal;
  writing-mode: lr-t;