Currently the testsuite does not have any test cases for browser integration, consequently it is possible for subtle regressions to occur undetected when a contributor is working on an issue. Utilising a third party testing framework such as selenium [1,2] to test interaction would reduce the chances of regressions occurring as the CI process would be more robust.

From an a SET perspective, such a testsuite would be beneficial as it would reduce the chances of issues failing QE due to regressions. Obviously there is a cost to writing such tests, however if each PR requires an accompanying test then the testsuite should evolve quickly.

[1] http://www.seleniumhq.org/
[2] http://www.gwtproject.org/articles/testing_methodologies_using_gwt.html