Multiline placeholder in textarea

[szuperaz]

• Chrome, Safari: if the placeholder requires two lines, the message input is still 1 line high, but it becomes scrollable
• Firefox: if the placeholder requires two lines, the message input is still 1 line high, but it's not scrollable, instead the test is cut-off

The logical behavior to me is that the textarea is at least as high as the placeholder text in it.