[webkit-dev] Dependency tracking in the Qt build system

On multiple occasions today we've been forced to manually do a clean build on the Qt build bot in order to work around test failures or crashes caused by bad builds. In the most recent case <http://trac.webkit.org/changeset/47165

reordered some virtual methods in Element. This resulted in 14 failures on the Qt buildbot: <http://build.webkit.org/builders/Qt%20Linux%20Release/builds/472 . Can someone with knowledge of the Qt build system please investigate what needs done to remove the need for this manual intervention in incremental builds so that keeping the Qt buildbot green is less painful?

- Mark