Make DOM geometry structs serializable (#38828)

Makes the following DOM geometry structs serializable:
- `DOMRect`
- `DOMRectReadOnly`
- `DOMQuad`
- `DOMMatrix`
- `DOMMatrixReadOnly`

Testing: Covered by WPT (`css/geometry/structured-serialization.html`).

---------

Signed-off-by: lumiscosity <averyrudelphe@gmail.com>

components/shared/script/lib.rs

@@ -182,7 +182,7 @@ pub enum ScriptThreadMessage {
         /// <https://html.spec.whatwg.org/multipage/#dom-messageevent-origin>
         source_origin: ImmutableOrigin,
         /// The data to be posted.
-        data: StructuredSerializedData,
+        data: Box<StructuredSerializedData>,
     },
     /// Updates the current pipeline ID of a given iframe.
     /// First PipelineId is for the parent, second is the new PipelineId for the frame.