feat(input): add animation to color change

[nnmrts]

feat(input): add animation to color change

add animation to color change when clicking inside an md-input field
previous behaviour was an instant color change, which doesn't harmonize with material design guidelines

[googlebot]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

📝 Please visit https://cla.developers.google.com/ to sign.

Once you've signed, please reply here (e.g. I signed it!) and we'll verify. Thanks.

---

• If you've already signed a CLA, it's possible we don't have your GitHub username or you're using a different email address. Check your existing CLA data and verify that your email is set on your git commits.
• If you signed the CLA as a corporation, please let us know the company's name.

[nnmrts]

I signed it!

[googlebot]

CLAs look good, thanks!

[clshortfuse]

@nnmrts Do you have a source for these bezier curve numbers?

[nnmrts]

@clshortfuse actually not, just used a random bezier curve, but perhaps we can use some of these: https://material.io/archive/guidelines/motion/duration-easing.html#duration-easing-natural-easing-curves

[Splaktar]

Looking at the input spec, there does appear to be an animation of the colors coming in, but it seems to go a step farther with the color changing via a ripple.

After testing this locally, I think that animating the color change is a good first step. I don't think that we'll get to the point of changing the color via a ripple.

So this LGTM once it's updated to use our variables for the duration and curve.

[Splaktar]

This build is failing because we switched from TravisCI to CircleCI. Rebasing the PR would resolve that, but it doesn't need to be rebased to merge this one line change.

[jelbourn]

LGTM

[googlebot]

All (the pull request submitter and all commit authors) CLAs are signed, but one or more commits were authored or co-authored by someone other than the pull request submitter.

We need to confirm that all authors are ok with their commits being contributed to this project. Please have them confirm that by leaving a comment that contains only @googlebot I consent. in this pull request.

Note to project maintainer: There may be cases where the author cannot leave a comment, or the comment is not properly detected as consent. In those cases, you can manually confirm consent of the commit author(s), and set the cla label to yes (if enabled on your project).

ℹ️ Googlers: Go here for more info.

[Splaktar]

@googlebot I consent.

[nnmrts]

Wow. After all these years.