Move ply and WebIDL into script_bindings (#43180)

This is required to publish script_bindings, since all files used during
codegen need to be there.
It might also be possible to generate the bindings ahead of time and
vendor them in-tree, but this seems painful to setup from a CI
perspective.
Since there don't seem to be any other users in-tree we can just vendor
into the script-bindings directory.

`ply` is licensed under the BSD 3 clause, and WebIDL under MPL-2.0, with
the licenses available in our cargo package. Both tools won't end up in
`servo` since they are build-time dependencies, so I believe we don't
need to adjust the crate license, or configure `about.toml`.

Testing: Should be covered by existing tests. We don't test if this
allows vendored builds or published builds.
Fixes: Partial fix for #43145

---------

Signed-off-by: Jonathan Schwender <schwenderjonathan@gmail.com>

components/script_bindings/Cargo.toml

@@ -3,10 +3,12 @@ name = "servo-script-bindings"
 build = "build.rs"
 version.workspace = true
 authors.workspace = true
-license.workspace = true
 edition.workspace = true
 publish.workspace = true
 rust-version.workspace = true
+# BSD-3-Clause comes from third_party/ply, which doesn't end up in any produced build-artifact,
+# but is used during the build via build.rs.
+license = "MPL-2.0 AND BSD-3-Clause"
 
 # https://github.com/rust-lang/cargo/issues/3544
 links = "script_bindings_crate"

components/script_bindings/build.rs

@@ -24,8 +24,8 @@ fn main() {
     println!("cargo::rerun-if-changed=webidls");
     println!("cargo::rerun-if-changed=codegen");
     println!("cargo::rerun-if-changed={}", css_properties_json.display());
-    println!("cargo::rerun-if-changed=../../third_party/WebIDL/WebIDL.py");
-    // NB: We aren't handling changes in `third_party/ply` here.
+    println!("cargo::rerun-if-changed=third_party/WebIDL/WebIDL.py");
+    println!("cargo::rerun-if-changed=third_party/ply");
 
     let status = find_python()
         .arg("codegen/run.py")

components/script_bindings/codegen/run.py

@@ -14,7 +14,7 @@ from typing import TYPE_CHECKING
 from collections.abc import Iterator
 
 SCRIPT_PATH = os.path.abspath(os.path.dirname(__file__))
-SERVO_ROOT = os.path.abspath(os.path.join(SCRIPT_PATH, "..", "..", ".."))
+SCRIPT_BINDINGS_ROOT = os.path.abspath(os.path.join(SCRIPT_PATH, ".."))
 
 FILTER_PATTERN = re.compile("// skip-unless ([A-Z_]+)\n")
 
@@ -24,15 +24,15 @@ if TYPE_CHECKING:
 
 def main() -> None:
     os.chdir(os.path.join(os.path.dirname(__file__)))
-    sys.path.insert(0, os.path.join(SERVO_ROOT, "third_party", "WebIDL"))
-    sys.path.insert(0, os.path.join(SERVO_ROOT, "third_party", "ply"))
+    sys.path.insert(0, os.path.join(SCRIPT_BINDINGS_ROOT, "third_party", "WebIDL"))
+    sys.path.insert(0, os.path.join(SCRIPT_BINDINGS_ROOT, "third_party", "ply"))
 
     css_properties_json, out_dir = sys.argv[1:]
     # Four dotdots: /path/to/target(4)/debug(3)/build(2)/style-*(1)/out
     # Do not ascend above the target dir, because it may not be called target
     # or even have a parent (see CARGO_TARGET_DIR).
     doc_servo = os.path.join(out_dir, "..", "..", "..", "..", "doc")
-    webidls_dir = os.path.join(SCRIPT_PATH, "..", "webidls")
+    webidls_dir = os.path.join(SCRIPT_BINDINGS_ROOT, "webidls")
     config_file = "Bindings.conf"
 
     import WebIDL