If a textarea has enough content to cause it to scroll, text entered becomes distorted. It is fixed by selecting the text, but any new text entered is distorted also. 1. FIll a textarea with enough content for scroll bars to appear. 2. Scroll to bottom of textarea and type, the text is distorted. 3. While the textarea has focus, press Cmd + A to select all text in the text area. The previously distorted text is now readable. 4. Place the cursor back at the bottom and type again - the new text is again distorted. For the text to appear distorted when typed, it doesn't have to be entered at the very end of the content, but it happens anywhere that would not be visible if the textarea is scrolled all the way to the top. This regressed somehwere between r17003 and r17019 (probably r17018).
Created attachment 11107 [details] testcase
My full-length feature film of this bug can be found here: http://bleepsoft.com/tyler/media/webkit_textarea_render_issue.mp4
Bug 11277 covers this issue (see the second test case in that bug). *** This bug has been marked as a duplicate of 11277 ***