Bug 865377.  Give EventTarget a chrome-only getter that returns its global.  r=smaug

The idea is that you then do things like t.dispatchEvent(new t.ownerGlobal.Event("something")).
Bug 877540.  Fix remaining unsafe reference hazards in browser code.  r=terrence
Bug 877216.  Add CallArgs-like structs for use in DOM specialized getters/setters/methods.  r=waldo
Bug 877390 - Do a blind null check. r=bz

Who knows why this happens, but this appears to be the culprit per crash
reports.