v2.6.0

• Implements anonymous user upgrade functionality with FirebaseUI.
• Implements isPendingRedirect needed to tell whether there is a pending redirect operation.
• Sanitizes display name in firebaseui.
• Clears cached app.getRedirectResult after signInWithRedirect or linkWithRedirect resolves.
• Fixes the bug when account linking doesn't get triggered in Cordova applications.
• Adds description for building localized npm builds and how to require them.
• Fixes dangling internal auth state when the firebaseui instance is reset.
• Updates closure open source builder to latest version fixing dependency on eval and older marked module which had some vulnerability issues.