servo: Merge #18489 - align selectors's features in geckolib and styl…

…o_tests (from froydnj:geckolib-feature-alignment); r=froydnj

Gecko would like to turn on the stylo layout tests (tests/unit/stylo) in
Gecko CI.  The plan for doing this is to add the tests as a
dev-dependency of Gecko's main Rust library, from which `cargo test` can
be run in the usual fashion.

Doing this creates problems for normal development, because the stylo
tests need the `selectors` crate to be compiled with `gecko_like_types`,
whereas the `geckolib` crate does not.  So if we compile `geckolib` in a
non-test build configuration, the `selectors` crate is compiled without
`gecko_like_types`...but then if we compile `geckolib` in a test build
configuration, cargo will evict the previous rlib for the `selectors`
crate and replace it with a `selectors` compiled with gecko_like_types.
And then compiling `geckolib` in a non-test configuration repeats the
process, and so forth.

Needless to say, this is highly annoying behavior.  It is due to a bug
in cargo:

rust-lang/cargo#3923

but it's not known when that bug will get fixed.  In the meantime, we
can just make sure that geckolib's `selectors` is compiled with the same
features as the `selectors` crate in the stylo tests.

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors

Source-Repo: https://github.com/servo/servo
Source-Revision: 1aa8be392b0ab8e7a8426f525361b40b69d70b4f

UltraBlame original commit: 962216b7844402a956a9b410fed0567506f96261

servo/ports/geckolib/Cargo.toml

@@ -196,6 +196,60 @@ parking_lot
 .
 4
 "
+#
+Turn
+on
+gecko_like_types
+because
+of
+so
+that
+crates
+which
+use
+this
+#
+crate
+and
+also
+dev
+-
+depend
+on
+stylo_tests
+get
+reasonable
+behavior
+#
+during
+rebuilds
+.
+See
+https
+:
+/
+/
+github
+.
+com
+/
+rust
+-
+lang
+/
+cargo
+/
+issues
+/
+3923
+#
+for
+the
+cargo
+problem
+behind
+this
+.
 selectors
 =
 {
@@ -212,6 +266,13 @@ components
 /
 selectors
 "
+features
+=
+[
+"
+gecko_like_types
+"
+]
 }
 servo_arc
 =