deviceScaleFactor option in newContext on Browser class isn't affecting the images

[ankur22]

Tested against: dbede12

The result of deviceScaleFactor of 1 should result in a blurry image as shown here:

[PW deviceScaleFactor set to 1]

And when it is set to 2, then it should look like this:

[PW deviceScaleFactor set to 2]

In xk6-browser the result of deviceScaleFactor is always the same regardless of the value set (the blurry image).

[ankur22]

This works with the default BrowserContext, but it doesn't work when a second context is created.