Fixed bug with incorrect counting of linebreaks in textarea

There is bug in FF, Chrome when linebreak is treated as 1 symbol when it's actually 2 symbols.

Because of this bug with such configuration:
```
<textarea maxlength="4">ff
f
</textarea>
```
browser does not allow us to enter more letters, but at the same time `simplyCounter` shows "you can enter *1* letter".

So this PR fixes this problem.