Add support for rendering video as image

[JacobMarshallPP]

When processing the video clone, we override the clone element with an image element, which either contains the successful render of the video element (drawn to a canvas), or a single 1x1 transparent pixel (stretched to the original element's dimensions).

For videos cross-origin, the transparent pixel is used, as the canvas which the video is drawn to becomes tainted. And for videos which don't match the dimensions of the element, the scaling & offset is applied to the image as well.

[JacobMarshallPP]

One strange thing with adding

Refreshing the window, or in my case the embedded

Not entirely sure at this current time what the issue is. I am going to do some profiling to see whether I can diagnose the actual root cause.

[marcusx2]

Why was this not merged yet?