Find some text in the current context. The implementation is
responsible for performing the find and highlighting the text.
| aPatText | The text to search for. |
| aSearchRange | A Range specifying domain of search. |
| aStartPoint | A Range specifying search start point. If not collapsed, we'll start from end (forward) or start (backward). |
| aEndPoint | A Range specifying search end point. If not collapsed, we'll end at end (forward) or start (backward). @retval A range spanning the match that was found (or null). |
Use “find entire words” mode by setting to a word breaker
or null, to disable “entire words” mode.