(1) add missing test:visual
(2) fix tooltip component default position: should apply `position` on option firstly.

fix: when label animation is not finished, start a new label animation, the label should not jump the the last final value.

Note: the implementation of "insert levelModel" is modified from "Tree.getModel"
to "beforeLink  nodeData.wrapMethod('getItemModel', ...)", because the former
one miss the case of `data.getItemModel`, which is needed in label formatter fetcher.