Export `setupDisposable` and `disposeDisposable` functions so that Disposables could invoke them directly.
Update sequence lib to cover ES6 Symbols.
Merge pull request #1717 from Gozala/context-menu-2-disosables@1070952

Bug 1070952 - Export `setupDisposable` and `disposeDisposable` r=@erikvold
Merge pull request #1718 from Gozala/context-menu-2-sequence@1070952

Bug 1070952 - Update sequence lib to cover ES6 Symbols. r=@erikvold
Bug 853085 Remove the unused registry module r=gozala
Bug 1094005 - remove unused panel code r=gozala
Disable unrelated errors coming from browser/skin a=@gozala