Bug 874502 part 1.  Fix browser-chrome tests to not assume synchronous closing of windows.  r=dolske
Bug 874502 part 2.  Fix addon sdk to not assume synchronous closing of windows.  r=mossop
Bug 874502 part 3.  Fix a11y tests to not assume synchronous window closing.  r=tbsaunde
Bug 874502 part 4.  Fix private browsing tests to not assume synchronous window closing.  r=jdm
Bug 874502 part 5.  Fix JP test-windows to handle on{activate,deactivate} after close().  r=mossop
Bug 874502 part 6.  Remove IsCallerChrome path for tearing down windows synchronously.  r=bzbarsky