Bug 850517 - Factor out child window lookup into a helper. r=mrbkap
Bug 850517 - Support named window access via Xray. r=mrbkap
Bug 850517 - Switch named children resolution to pure getters on the global scope polluter. r=mrbkap

Note that this causes us to throw when assigning to named children, but this is
spec-correct.
Bug 850517 - Remove nsWindowSH::GetProperty. r=mrbkap

It no longer does anything useful.
Bug 850517 - Propagate ifr.setAttribute('name', 'foo') to the docshell. r=bz

This is correct per-spec. From HTML5's "The iframe element":

"Whenever the name attribute is set, the nested browsing context's name
must be changed to the new value. If the attribute is removed, the
browsing context name must be set to the empty string."
Bug 850517 - Tests. r=bz