Issue with getComputedStyle / breaking tests

[karimbeyrouti]

Using getComputedStyle with browser service breaks tests, this is cause by the browser service proxying values, since getComputedStyle expects a HTMLElement and not a proxy it thows the following error:

Failed to execute 'getComputedStyle' on 'Window': parameter 1 is not of type 'Element'.

with the following code

let cssVar = getComputedStyle(this.window.document.documentElement).getPropertyValue( '--css-var', );

[NullVoxPopuli]

I don't think this is something you'd want to not use the real implementation for.
Can you describe more what you're trying to do?