Canonical URL for "latest" page wrong?

[kevmoo]

https://pub.dartlang.org/documentation/angular/latest/

Has a canonical URL of https://pub.dartlang.org/documentation/angular/4.0.0+2//index.html

1 - Extra slash is sad
2 - Doesn't feel like it aligns w/ discussion here #1017 (comment)

We want the canonical URL to be stable – https://pub.dartlang.org/documentation/angular/latest/ – so search engines aren't constantly linking to different pages as the content updates

[mit-mit]

cc @isoos