[IE] Find result highlighting problem

[Garry Yao]

Previous highlight marking style is not removed when search more than twice.

Reproducing Procedures

1. Open the replace by class example page;
2. Open 'Find' dialog, search for 'some';
3. Keep the dialog open, another search for 'are'

• Actual Result: Search results from both matching are marked.

[Artur Formella]

DUP of #3450.