Auto merge of #25354 - lberrymage:dom-domroot-lint-check, r=jdm

Add &DomRoot<T> lint check

So far, the lint check code appears to work as intended. However, some trait implementations require modification to pass the lint check and I'm not sure how to fix these. Commit 92cf5d5 attempts to correct one of the implementations, but fails to compile with error:
```
  --> components/script/dom/servoparser/xml.rs:76:36
   |
76 |         tree_builder.trace_handles(&tracer);
   |                                    ^^^^^^^ expected struct `dom::bindings::root::Dom`, found struct `dom::node::Node`
   |
   = note: expected struct `dom::bindings::root::Dom<dom::node::Node>`
              found struct `dom::node::Node`
   = note: required for the cast to the object type `dyn html5ever::tree_builder::Tracer<Handle = dom::bindings::root::Dom<dom::node::Node>>`
```
I've tried to debug further but to no avail. I also don't want to mangle too much existing code unnecessarily. Any help is appreciated.

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- [ ] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
`./mach test-tidy --all` does, and some are directly related to this PR
- [ ] These changes fix #25342
The fix is a WIP

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- [X] There are tests for these changes

Note that I will clean up the commit history before the final PR.
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python/tidy/servo_tidy/tidy.py

@@ -623,6 +623,7 @@ def check_rust(file_name, lines):
             (r"DomRefCell<Heap<.+>>", "Banned type DomRefCell<Heap<T>> detected. Use MutDom<T> instead", no_filter),
             # No benefit to using &Root<T>
             (r": &Root<", "use &T instead of &Root<T>", no_filter),
+            (r": &DomRoot<", "use &T instead of &DomRoot<T>", no_filter),
             (r"^&&", "operators should go at the end of the first line", no_filter),
             # This particular pattern is not reentrant-safe in script_thread.rs
             (r"match self.documents.borrow", "use a separate variable for the match expression",

python/tidy/servo_tidy_tests/rust_tidy.rs

@@ -38,7 +38,7 @@ impl test {
         }
     }
 
-    fn test_fun2(y : &String, z : &Vec<f32>, r: &Root<isize>) -> () {
+    fn test_fun2(y : &String, z : &Vec<f32>, r: &Root<isize>, s: &DomRoot<isize>) -> () {
         let x = true;
         x
             && x;

python/tidy/servo_tidy_tests/test_tidy.py

@@ -112,6 +112,7 @@ class CheckTidiness(unittest.TestCase):
         self.assertEqual('use &[T] instead of &Vec<T>', next(errors)[2])
         self.assertEqual('use &str instead of &String', next(errors)[2])
         self.assertEqual('use &T instead of &Root<T>', next(errors)[2])
+        self.assertEqual('use &T instead of &DomRoot<T>', next(errors)[2])
         self.assertEqual('encountered function signature with -> ()', next(errors)[2])
         self.assertEqual('operators should go at the end of the first line', next(errors)[2])
         self.assertNoMoreErrors(errors)