To reproduce: 1. Go to http://webkit.org/ 2. Size the window so that it is wider than the content requires (you should have no horizontal scrollbar) 2. Enter this in the address field and press Enter: javascript:document.documentElement.style.webkitPerspective = "300px" In Debug builds, the right side of the page turns red, indicating that WebKit isn't painting this region anymore. In Release builds, it turns white. This doesn't happen on Mac.
<rdar://problem/7638050>