Cherry picks for 1.6

[ebidel]

R: all

Some cherry picks from master so they make it in 1.6. Of note, this includes:

• update-notifier - that'll be nice to have in place when we do the next major release
• report: legend at the bottom
• report: print functionality fixes
• report: adjustments to colors and icon sizes for a11y

All of these have already landed.

[googlebot]

So there's good news and bad news.

👍 The good news is that everyone that needs to sign a CLA (the pull request submitter and all commit authors) have done so. Everything is all good there.

😕 The bad news is that it appears that one or more commits were authored by someone other than the pull request submitter. We need to confirm that they're okay with their commits being contributed to this project. Please have them confirm that here in the pull request.

Note to project maintainer: This is a terminal state, meaning the cla/google commit status will not change from this state. It's up to you to confirm consent of the commit author(s) and merge this pull request when appropriate.

[paulirish]

sgtm

i'm only slightly hesitant about update-notifier but otherwise feel good.

[paulirish]

I think we should probably also get #1918 cherrypicked so that WPT wont be lying about HTTPS to err'one.

[ebidel]

@paulirish that one doesnt merge cleanly because of the changes in 174766f, removing the formatters, and the move to template partials. Lots of stuff happened.

The other thing we could do is just roll the current master as the next release. Of course, hold up on merging #1896 until we do a release.