script: Move CSS DOM interfaces to script/dom/css/ (#40241)

Moves interfaces defined by the CSS spec to the `script/dom/css/` module
from `script/dom/`.

Testing: Just a refactor shouldn't need any testing
Fixes: Partially #38901

Signed-off-by: WaterWhisperer <waterwhisperer24@qq.com>

components/script/dom/css/cssstylevalue.rs

@@ -0,0 +1,63 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use cssparser::{Parser, ParserInput};
+use dom_struct::dom_struct;
+use servo_url::ServoUrl;
+
+use crate::dom::bindings::codegen::Bindings::CSSStyleValueBinding::CSSStyleValueMethods;
+use crate::dom::bindings::reflector::{Reflector, reflect_dom_object};
+use crate::dom::bindings::root::DomRoot;
+use crate::dom::bindings::str::DOMString;
+use crate::dom::globalscope::GlobalScope;
+use crate::script_runtime::CanGc;
+
+#[dom_struct]
+pub(crate) struct CSSStyleValue {
+    reflector: Reflector,
+    value: String,
+}
+
+impl CSSStyleValue {
+    fn new_inherited(value: String) -> CSSStyleValue {
+        CSSStyleValue {
+            reflector: Reflector::new(),
+            value,
+        }
+    }
+
+    pub(crate) fn new(
+        global: &GlobalScope,
+        value: String,
+        can_gc: CanGc,
+    ) -> DomRoot<CSSStyleValue> {
+        reflect_dom_object(
+            Box::new(CSSStyleValue::new_inherited(value)),
+            global,
+            can_gc,
+        )
+    }
+}
+
+impl CSSStyleValueMethods<crate::DomTypeHolder> for CSSStyleValue {
+    /// <https://drafts.css-houdini.org/css-typed-om-1/#CSSStyleValue-stringification-behavior>
+    fn Stringifier(&self) -> DOMString {
+        DOMString::from(&*self.value)
+    }
+}
+
+impl CSSStyleValue {
+    /// Parse the value as a `url()`.
+    /// TODO: This should really always be an absolute URL, but we currently
+    /// return relative URLs for computed values, so we pass in a base.
+    /// <https://github.com/servo/servo/issues/17625>
+    pub(crate) fn get_url(&self, base_url: ServoUrl) -> Option<ServoUrl> {
+        let mut input = ParserInput::new(&self.value);
+        let mut parser = Parser::new(&mut input);
+        parser
+            .expect_url()
+            .ok()
+            .and_then(|string| base_url.join(&string).ok())
+    }
+}