test($compile): work around Chrome issue with reported size for `<foreignObject>`

Since Chrome 53-57+, the reported size of `<foreignObject>` elements and their
descendants is affected by global display settings (e.g. font size) and browser
settings (e.g. default zoom level). This could cause tests incorrectly failing
due to such settings.

In order to avoid false negatives, we now compare against the size of the
equivalent, hand-written SVG instead of fixed widths/heights.

Fixes #15333

Closes #15458