Bug 957577 - [Contacts] navigation.js should support several concurrent instances of navigationStack.
Merge pull request #15107 from gtorodelvalle/contacts-bug-957577-multiple-navigationStack-instances

Bug 957577 - [Contacts] navigation.js should support several concurrent instances of navigationStack
Bug 951331 - [Messages][Drafts] MMS indicator missing for MMS drafts in existing (non-threadless) threads