Tests that requestAnimationFrame is throttled in subframes are inside scrolled overflow scroll On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". Frame is initially inside the viewport so requestAnimationFrame should not be throttled PASS testFrame.contentWindow.internals.requestAnimationFrameThrottlingReasons() is "[Unthrottled]" Scrolling overflow. requestAnimationFrame should still not be throttled PASS testFrame.contentWindow.internals.requestAnimationFrameThrottlingReasons() is "[Unthrottled]" PASS successfullyParsed is true TEST COMPLETE