Cleanup redundant Math.max/min calls in DefaultHighlighter

Method javax.swing.text.DefaultHighlighter#changeHighlight
```
        if (p1 < p0) {
            throw new BadLocationException("Invalid end of the range", p1);
        }
        ...
        safeDamageRange(Math.min(p0, p1), Math.max(p0, p1));
```
This Math.max and Math.min calls are redundant, because order of p0 and p1 is checked in method pre-conditions.
Checks were added under JDK-6771184