feat(material/snack-bar): Switch snack-bar implementation to use MDC

[mmalerba]

Old implementation is still available under @angular/material/legacy-snack-bar

BREAKING CHANGE:

• DOM and CSS classes for mat-snack-bar have changes
• Typescript API is largely the same but may have minor differences
• See the MDC migration guide for more information about the changes and
  how to migrate your app (TODO: link when available)

[mmalerba]

@crisbeto do you know whats up with this test failure: "theming api should warn if default density styles are duplicated"

It looks like the mdc-button density styles are missing. I did touch those styles a bit because I found that button density was under "unmigrated-component-densities" and icon-button, fab were just missing. I'm not sure why the test is failing though. If anything my change should have fixed it since it added the missing mixins

[crisbeto]

I would have to dig into why that test is failing, but from what I can tell, it is related to MDC's styles, because excluding this mixin fixes the test failure https://github.com/angular/components/blob/main/src/material/button/_icon-button-theme.scss#L55. Maybe it's being generated under the wrong selector?

[andrewseguin]

Yeah I remember getting that when I had the wrong names in private-check-duplicate-theme-styles

[mmalerba]

Based on my understanding of the test, it looks like @include angular-material-density(0); is somehow producing a different result for mat-icon-button than @include angular-material-theme((color: null));. This is odd because it produces the same result for every other component

[mmalerba]

Mystery solved: the function we had to compare CSS output didn't know how to handle comments, which was causing it to say that the outputs weren't equivalent

[wagnermaciel]

lgtm

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}