Auto merge of #25837 - servo:jdm-patch-40, r=Manishearth

Remove XR canvas dirtying step.

Alan tells me that this is no longer necessary, and it causes layout operations to appear in immersive mode profiles when there should not be any.

components/script/dom/xrsession.rs

@@ -5,7 +5,6 @@
 use crate::dom::bindings::callback::ExceptionHandling;
 use crate::dom::bindings::cell::DomRefCell;
 use crate::dom::bindings::codegen::Bindings::NavigatorBinding::NavigatorBinding::NavigatorMethods;
-use crate::dom::bindings::codegen::Bindings::WebGLRenderingContextBinding::WebGLRenderingContextMethods;
 use crate::dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::WindowMethods;
 use crate::dom::bindings::codegen::Bindings::XRReferenceSpaceBinding::XRReferenceSpaceType;
 use crate::dom::bindings::codegen::Bindings::XRRenderStateBinding::XRRenderStateInit;
@@ -16,7 +15,6 @@ use crate::dom::bindings::codegen::Bindings::XRSessionBinding::XRFrameRequestCal
 use crate::dom::bindings::codegen::Bindings::XRSessionBinding::XRSessionMethods;
 use crate::dom::bindings::codegen::Bindings::XRSessionBinding::XRVisibilityState;
 use crate::dom::bindings::codegen::Bindings::XRSystemBinding::XRSessionMode;
-use crate::dom::bindings::codegen::Bindings::XRWebGLLayerBinding::XRWebGLLayerMethods;
 use crate::dom::bindings::error::{Error, ErrorResult};
 use crate::dom::bindings::inheritance::Castable;
 use crate::dom::bindings::refcounted::Trusted;
@@ -25,8 +23,6 @@ use crate::dom::bindings::root::{Dom, DomRoot, MutDom, MutNullableDom};
 use crate::dom::event::Event;
 use crate::dom::eventtarget::EventTarget;
 use crate::dom::globalscope::GlobalScope;
-use crate::dom::node::Node;
-use crate::dom::node::NodeDamage;
 use crate::dom::performance::reduce_timing_resolution;
 use crate::dom::promise::Promise;
 use crate::dom::xrframe::XRFrame;
@@ -412,14 +408,6 @@ impl XRSession {
             "WEBXR PROFILING [raf execute]:\t{}ms",
             (time::precise_time_ns() - raf_start) as f64 / 1_000_000.
         );
-
-        // If the canvas element is attached to the DOM, it is now dirty,
-        // and we need to trigger a reflow.
-        base_layer
-            .Context()
-            .Canvas()
-            .upcast::<Node>()
-            .dirty(NodeDamage::OtherNodeDamage);
     }
 
     fn update_inline_projection_matrix(&self) {