Make it possible to evaluate JS with the v4 tool the QML way

Change-Id: I2a40e82612c2da1b52a37cbff2507951e4ac0349
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Fix url test in qqmllanguage

In V4 URLs were mapped to strings, with V8 they were mapped to opaque
variants, which is also what we do with v4 at the moment. In the future
we want to provide a real JS API for URLs, but that is a feature that
should be discussed in a wider scope and developed on the dev branch.

Change-Id: I17660066b2797239eddebad03f49ffa424f86f78
Reviewed-by: Lars Knoll <lars.knoll@digia.com>