(bug 57388) first click in [Start a new topic] jumps to textarea below

Alternative method to focus textarea

Textarea focus should not be handled by the editor object itself.
Reason: clicking the "add new topic" title input field will add a textarea which
loads an editor, which will steal focus from the title input field.

Instead, focus should be applied earlier in the code.

Meanwhile also changed how initial height is set; better to re-use same code.

And I've removed setSelectionRange( 0, 0 ). Not really sure it that's ok, but I
couldn't really figure out why that was needed (I wouldn't expect the cursor to
be in front of all text, but that may just be me)

Bug: 57388
Change-Id: I62b767c922441a70e5bafe557d498f74c306a4ee
Merge "(bug 57388) first click in [Start a new topic] jumps to textarea below"