Log in to Tumblr (yeah, I know). Click the "Aa" button to start a new text post. Click around the three text fields: title, your text here, and tags. Cursor will appear on title and tags, but does not appear on "your text here", even though the text area is focused and will accept typed input. Same thing happens when moving between fields with the tab key -- the main text area does not show your cursor until you start typing, even though the field has focus.
I can reproduce with 7.1.3, so it's not a recent regression. Works in Firefox.
<rdar://problem/19847012>