Browser tests are currently not executed for the Edge browser on
Windows. Some of the existing tests are not working for Edge, as they
make assumptions that are incompatible with WebView API (such as
executing operations on the browser from within browser callback).

In order to prepare the tests to be executed for Edge as well, this
change disables the incompatible tests when being executed for Edge.

Contributes to
https://github.com/eclipse-platform/eclipse.platform.swt/issues/671