Fix tst_QWebEnginePage's use of evaluateJavaScript

Mostly speculative autotest adjustments due to lacking features

Change-Id: I5b0cfa8fb586ae4531327c21d03b064d9c307d06
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>
WebPage: Implement javaScriptConsoleMessage

And unskip the corresponding autotest.

Change-Id: Ida2dcee38b261b2ba4ad0c5c016f5510ed1590a4
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>
Make the QWebEngineFrame tests pass

The unskipped ones that is.
This highlights some behavior changes, notably the fact that loadFinished
now fires as many times as there were loads initiated.

Change-Id: I75665cdf06f4692fbeccb5227aa056e598038748
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>