Auto merge of #21181 - nupurbaghel:update_source_set, r=jdm

Implement update source set & select image source

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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 #11416 (github issue number if applicable).

- [x] These changes require tests but cannot be written until implementation of responsive images is complete

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components/script/dom/bindings/trace.rs

@@ -48,6 +48,7 @@ use dom::bindings::root::{Dom, DomRoot};
 use dom::bindings::str::{DOMString, USVString};
 use dom::bindings::utils::WindowProxyHandler;
 use dom::document::PendingRestyle;
+use dom::htmlimageelement::SourceSet;
 use encoding_rs::{Decoder, Encoding};
 use euclid::{Transform2D, Transform3D, Point2D, Vector2D, Rect, TypedSize2D, TypedScale};
 use euclid::Length as EuclidLength;
@@ -427,6 +428,7 @@ unsafe_no_jsmanaged_fields!(ScriptToConstellationChan);
 unsafe_no_jsmanaged_fields!(InteractiveMetrics);
 unsafe_no_jsmanaged_fields!(InteractiveWindow);
 unsafe_no_jsmanaged_fields!(CanvasId);
+unsafe_no_jsmanaged_fields!(SourceSet);
 
 unsafe impl<'a> JSTraceable for &'a str {
     #[inline]