Disable testReplaceItemNoEvent for HtmlUnit platform

When running tests with HtmlUnit, when testReplaceItemNoEvent adds a new
history token with the fire event set to false, the event is not fired
during the test, but some time after, and testEmptyHistoryTokens sees it.

For some reason and randomly testEmptyHistoryTokens does not fail, perhaps
because of the order how the tests are run changes, or depending on how busy
the server is.

Change-Id: I52ee77616770e42e2a33a71ffe4125ad80940bcb