Auto merge of #20012 - alexfjw:avoid_Window-GetComputedStyle_when_checking_for_display-none, r=emilio

Avoid `Window::GetComputedStyle` when checking for `display: none`

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Refactored Window::GetComputedStyle to use Element::Style.

Not sure which tests are relevant, but I've ran the dom, fetch & 2dcontext wpt tests. They don't seem to give errors.

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #19885.

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- [x] These changes do not require tests because it's a refactoring task

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components/script/script_thread.rs

@@ -25,7 +25,6 @@ use devtools_traits::{ScriptToDevtoolsControlMsg, WorkerId};
 use devtools_traits::CSSError;
 use document_loader::DocumentLoader;
 use dom::bindings::cell::DomRefCell;
-use dom::bindings::codegen::Bindings::CSSStyleDeclarationBinding::CSSStyleDeclarationMethods;
 use dom::bindings::codegen::Bindings::DocumentBinding::{DocumentMethods, DocumentReadyState};
 use dom::bindings::codegen::Bindings::EventBinding::EventInit;
 use dom::bindings::codegen::Bindings::TransitionEventBinding::TransitionEventInit;
@@ -1926,7 +1925,7 @@ impl ScriptThread {
         node.dirty(NodeDamage::NodeStyleDamaged);
 
         if let Some(el) = node.downcast::<Element>() {
-            if &*window.GetComputedStyle(el, None).Display() == "none" {
+            if !el.has_css_layout_box() {
                 return;
             }
         }