RFR: 8218973: SVG with masking is not rendering image with mask effect [v13]

[Kevin Rushforth]

On Thu, 17 Sep 2020 06:35:16 GMT, Arun Joseph <ajoseph at openjdk.org> wrote:

>> The fix works when the shape is displayed initially on the screen, but fails when we scroll the image off-screen and
>> then, back. To see the issue, you need to either rotate the gradient transform (by 90 degrees) or use a circle (any
>> shape other than a rectangle) as the mask shape, as this bug can't be seen using a mask rectangle.
>
> To reproduce the above issue, you can either modify `<linearGradient id='Gradient' gradientTransform="rotate(90)">` or
> `<mask id='Mask3'> <circle cx='100' cy='300' r="100" fill='url(#Gradient)' /> </mask>` in `svgMask.html` and resize the
> window for scrolling.

This PR is on hold. It can be reopened or a new PR can be sent as and when it is ready to proceed.

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PR: https://git.openjdk.java.net/jfx/pull/213