#235 Support for windows.performance -> Google Analytics

[Jason Durheim]

At a high level, the feature I'm looking for here is for htmlunit to have enough of the windows.performance features implemented out such that if a webpage has GoogleAnalytics configured to track the users accessing that page, htmlunit will pass page timing data to GoogleAnalytics, page load speeds, etc.

I'm currently using 2.22, and GoogleAnalytics picks up the users accessing the page, page views down to the specific URL, but all page load speed are 0 seconds. Per the GADoc, "Site speed can only be tracked from browsers that support the HTML5 Navigation Timing interface". Based on closed bugs 1739 and 1756 I'm guessing it has not been implemented enough such that GA will get the necessary timing data.

Our preference is to use htmlunit over something like phantomjs (for which GA does pick up page speed stats), but won't work for our performance testing solution without data getting loaded into Google Analytics.

[RBRi]

implemented in 2.21