Follow the HTML speficication and add missing 'transferToImageBitmap'
method to OffscreenCanvas interface.
https://html.spec.whatwg.org/multipage/#dom-offscreencanvas-transfertoimagebitmap
Testing: Improvements in the following tests
- html/canvas/offscreen/compositing/2d.composite.grid*
- html/canvas/offscreen/fill-and-stroke-styles/2d.gradient*
- html/canvas/offscreen/manual/the-offscreen-canvas/offscreencanvas*
- html/canvas/offscreen/reset/2d.reset*
- html/canvas/offscreen/text/2d.text*
Fixes (partially): #34111
Signed-off-by: Andrei Volykhin <andrei.volykhin@gmail.com>
Most tests were only being run for layout-2013, not for layout-2020.
This wasn't great since layout-2020 is now the default.
So this patch unifies the lists of included tests for both layouts.
For layout-2013 this implies adding css/css-content/, css/css-logical/
and css/css-masking/clip/.
For layout-2020 this implies adding several additional css tests, and
also tests like dom/, js/, html/, etc.
