Currently the compiler treats `@page` rules in the same way as `@media`, however that is incorrect and it results in invalid CSS, because `@page` allows style declarations at the root (e.g. `@page (margin: 50%) {}`) and it only allows a limited set of at-rules to be nested into it. Given these restrictions, we can't really encapsulate the styles since they apply at the document level when the user tries to print.
These changes make it so that `@page` rules are preserved so that we don't break the user's CSS.
More information: https://www.w3.org/TR/css-page-3Fixes#26269.
PR Close#41915
After this, neither @angular/compiler nor @angular/comnpiler-cli depend
on @angular/core.
This add a duplication of some interfaces and enums which is stored
in @angular/compiler/src/core.ts
BREAKING CHANGE:
- `@angular/platform-server` now additionally depends on
`@angular/platform-browser-dynamic` as a peer dependency.
PR Close#18683