Support IE8 and Edge

[joescii]

Both of these are supported by HtmlUnit. When we use either, we get this error:

[info] Running JavaScript tests on InternetExplorer8...
[warn] Script is not JavaScript (type: application/javascript, language: javascript). Skipping execution.
[warn] Script is not JavaScript (type: application/javascript, language: javascript). Skipping execution.
[warn] Script is not JavaScript (type: application/javascript, language: javascript). Skipping execution.
[warn] Script is not JavaScript (type: application/javascript, language: javascript). Skipping execution.
[warn] Script is not JavaScript (type: application/javascript, language: javascript). Skipping execution.