Full screen videos are hidden when a parent node has animation

• Component: Layout and Rendering
• Status: RESOLVED CONFIGURATION CHANGED

[David Zhang]

Steps to reproduce:
1. Go to https://www.appdirect.com/apps/577#!overview
2. Click on "Watch Demo"
3. Click "Full screen" in the Youtube player

Expected:
Full screen video player

Actual:
Browser is full screen, video player is hidden

Workaround:
Either removing the animation/-webkit-animation property from the .adb-modal selector, or adding this CSS solves the problem:

:-webkit-full-screen-ancestor:not(iframe) {
    animation-name: none !important;
}

So I believe the problem is just that this style is missing from WebCore/css/fullscreen.css, since it already clears transform and transition for the same selector.

As David says, I think it makes sense to add: 

:-webkit-full-screen-ancestor:not(iframe) {
    animation: none !important;
}

since the reset is already applied to other properties that affects stacking context like transition and transform.

[Radar WebKit Bug Importer]

<rdar://problem/31436850>

[Jon Lee]

This bug no longer reproduces for me on a recent build.