[css-view-transitions-1] Update capture rendering characteristics (#9059)

* Use keyframes to specify plus-lighter blending for cross-fades

* Fix indentation

* [css-view-transitions-1] Update capture rendering characteristics

We don't need to specify that the canvas origin for painting an element maps to the ink overflow rectangle. The algorithm already clarifies that the image is the element's ink overflow rectangle via : "Return the portion of the canvas that includes element’s ink overflow rectangle as an image".

Author: khushalsagar

css-view-transitions-1/Overview.bs

@@ -1646,8 +1646,6 @@ urlPrefix: https://wicg.github.io/navigation-api/; type: interface;
 	<div algorithm>
 		The <dfn>capture rendering characteristics</dfn> are as follows:
 
-		* The origin of |element|'s [=ink overflow rectangle=] is anchored to canvas origin.
-
 		* If the referenced element has a transform applied to it (or its ancestors),
 			then the transform is ignored.