Update api.TextMetrics compatibility for Chrome and Edge

[1valdis]

• Summarize your changes: Chrome has four more properties from TextMetrics enabled by default since release 77 of desktop, Android, and Webview browsers.

• Data: link to resources that verify support information: Chrome Platform Status: New TextMetrics object in canvas says that actualBoundingBoxLeft, actualBoundingBoxRight, actualBoundingBoxAscent and actualBoundingBoxDescent are enabled by default since release 77.

• Data: if you tested something, describe how you tested with details like browser and version:
  I made a quick test on Chrome 79 desktop:

document.createElement('canvas').getContext('2d').measureText('testing metrics')

It gives an object with the following properties:

width: 64.462890625
actualBoundingBoxLeft: -0.1123046875
actualBoundingBoxRight: 64.1015625
actualBoundingBoxAscent: 7.1728515625
actualBoundingBoxDescent: 2.2119140625

• Review the results of the linter and fix problems reported (If you need help, please ask in a comment!): done, all green.

• Link to related issues or pull requests, if any: haven't found anything related to TextMetrics in Chrome 77.

[1valdis]

I wonder if instead of removing flag data, I should make them arrays of objects, as such:

[
  {
    "version_added": "77"
  },
  {
    "version_added": true,
    "version_removed": "77",
    "flags": [
      {
        "type": "preference",
        "name": "Experimental Web Platform Features"
      }
    ]
  }
]

[1valdis]

Is anyone here? I see other PRs being created and merged and mine just getting ignored for a week 🤔

[Elchi3]

Hey, sorry for the slow response, but as you've seen there are a lot of PRs here, so sometimes things can take a while.

I wonder if instead of removing flag data, I should make them arrays of objects, as such:

Yeah, a range could be done here, but given we don't have the start of the range for when it was behind a flag, I wonder how useful this one really is.

For Edge, you could change the false values to 79, given Edge uses Chromium 79 now :)

[1valdis]

@Elchi3

I wonder how useful this one really is.

Yep I saw ranges while a released feature was behind a flag, but those were with specific versions. Although the data that this was behind a flag earlier, even though specific versions are unknown, could be useful for some historical reasons. So should I leave it as it is or create an array?

I'll edit Edge data soon.

[Elchi3]

So should I leave it as it is or create an array?

I wish we had a clear policy about this, but we haven't come to an agreement on this matter yet, see #3318.
If you're a fan of preserving data, then you could add the arrays. However as we're lacking a policy, I would also be fine with the PR as it is now.

I'll edit Edge data soon.

Thank you!

[1valdis]

@Elchi3

If you're a fan of preserving data, then you could add the arrays.

Yep I like that better. You never know who might need it, and for what bizarre reasons :). The PR should be finished in a few hours. Should I somehow notify you when it's done?

[Elchi3]

Thanks for your work and going the extra mile here!
Feel free to notify me, I will do my best to review it timely :)

[1valdis]

@Elchi3 done.

Note though that I haven't tested the change for Edge, so I'm counting on your data. I will rename the PR to reflect that it touches Edge too.

[Elchi3]

Thank you! Nice work! 👍