Add test for overconstrained sticky view rectangle

[johannesodland]

There seems to be no tests for when the border box of the sticky element is taller than the initial sticky view rectangle.

In that case

the effective end-edge inset in the affected axis is reduced (possibly becoming negative) to bring the sticky view rectangle’s size up to the size of the border box in that axis

https://www.w3.org/TR/css-position-3/#sticky-pos

[johannesodland]

@smfr I added a test for when the border box of the sticky element is taller than the sticky view rectangle. Do you mind reviewing? It seems that we don't have browser interoperability here.