Media uploader message line-height is too tight

[Nao]

The new in-editor uploader shows "Drop files to upload" message when a file is drugged. When the window width is not enough to show the message in one line, the text wraps around, causing the first and second lines to overwrap.

In the case of Japanese translation, this happens on a fairly wide window (e.g 1024px).

Before:

I'll attach a CSS patch to set line-height to this h3 element.

After:

[nacin]

In 27773:

Editor: Fix line height on 'Drop files to upload'.

props Nao.
fixes #27541.