Each click should have the effect described below, for "text one" in the first
round and then "text two" for the second round. The effect change is due to
style tag or style link change in the HTML imports
1. text turn gray. (Not working via safeview, insertRule/deleteRule failure.)
2. text color removed.
3. no visual change, a div node removed.
4. text style change because a new style node is added.
5. no visual change because a div node is added.
6. text style change (to underline) because style text is modified.