Auto merge of #18213 - aethanyc:improve-debug-log, r=emilio

Improve debug log related to selector matching

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

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- [ ] There are tests for these changes OR
- [x] These changes do not require tests because it only modifies debug log

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components/style/style_resolver.rs

@@ -356,7 +356,7 @@ where
         );
 
         if log_enabled!(Trace) {
-            trace!("Matched rules:");
+            trace!("Matched rules for {:?}:", self.element);
             for rn in rule_node.self_and_ancestors() {
                 let source = rn.style_source();
                 if source.is_some() {