Since WebKit is now supposed to paint on load (currently disabled because of <rdar://problem/5092361> but simulated by DumpRenderTree), DumpRenderTree ends up rendering each test to the window in addition to rendering to the offscreen buffer.
Created attachment 17244 [details] Paint only once (unless testing repaint) I verified that the painting code is run in --leaks mode simply by using Expose to bring in DRT's "offscreen" window and verifying that the tests are being rendered. I also verified that repaint tests work.
Comment on attachment 17244 [details] Paint only once (unless testing repaint) r=me
Fixed in <http://trac.webkit.org/projects/webkit/changeset/27766>.
Nice.