script: Notify PinchZoom resizes to ScriptThread's VisualViewport (#41754)

Continuing the implementation of `VisualViewport`, the resizing of
`PinchZoom` should be notified to `ScriptThread` to update the
`VisualViewport` interface and to fire the appropriate JS event. Top
level `Window`/`Pipeline` would have a `VisualViewport` interface that
mirrors the `PinchZoom` viewport, while nested `Window` would have a
default value that represent layout viewport of the relevant iframe. The
`VisualViewport` of an iframe is updated after each reflow that
calculate the rectangle of the iframe.

The updates of DOM's `VisualViewport` occurs immediately (instead of
waiting for the event loop like the viewport) but integrates with the
event loop for the JS events. This behavior would helps with the fact
that `VisualViewport` needs to be updated both when it is scrolled or
resized.

Testing: Existing WPTs and new unit test.
Part of: https://github.com/servo/servo/issues/41341

---------

Signed-off-by: Jo Steven Novaryo <steven.novaryo@gmail.com>

components/script/script_thread.rs

@@ -79,7 +79,7 @@ use net_traits::{
     FetchMetadata, FetchResponseMsg, Metadata, NetworkError, ResourceFetchTiming, ResourceThreads,
     ResourceTimingType,
 };
-use paint_api::{CrossProcessPaintApi, PipelineExitSource};
+use paint_api::{CrossProcessPaintApi, PinchZoomInfos, PipelineExitSource};
 use percent_encoding::percent_decode;
 use profile_traits::mem::{ProcessReports, ReportsChan, perform_memory_report};
 use profile_traits::time::ProfilerCategory;
@@ -1935,6 +1935,9 @@ impl ScriptThread {
                     EmbedderMsg::AccessibilityTreeUpdate(webview_id, tree_update),
                 );
             },
+            ScriptThreadMessage::UpdatePinchZoomInfos(id, pinch_zoom_infos) => {
+                self.handle_update_pinch_zoom_infos(id, pinch_zoom_infos, CanGc::from_cx(cx));
+            },
         }
     }
 
@@ -4050,6 +4053,20 @@ impl ScriptThread {
             .embedder_controls()
             .handle_embedder_control_response(id, response, can_gc);
     }
+
+    pub(crate) fn handle_update_pinch_zoom_infos(
+        &self,
+        pipeline_id: PipelineId,
+        pinch_zoom_infos: PinchZoomInfos,
+        can_gc: CanGc,
+    ) {
+        let Some(window) = self.documents.borrow().find_window(pipeline_id) else {
+            warn!("Visual viewport update for closed pipeline {pipeline_id}.");
+            return;
+        };
+
+        window.maybe_update_visual_viewport(pinch_zoom_infos, can_gc);
+    }
 }
 
 impl Drop for ScriptThread {