If a mouse event is targeting an iframe, forward it to the iframe's inner window

Fixes #8759.

This adds a slow path for cases where the compositor's layer-based hit testing
is incorrect.  To optimize for this case, we could instead replace the
layer hit testing with display-list hit testing done in the paint task.

1 files changed, 5 insertions, 0 deletions

diff --git a/components/script/dom/htmliframeelement.rs b/components/script/dom/htmliframeelement.rs
index 78400b6d49a..fe07d28a198 100644
--- a/components/script/dom/htmliframeelement.rs
+++ b/components/script/dom/htmliframeelement.rs
@@ -186,6 +186,11 @@ impl HTMLIFrameElement {
     }
 
     #[inline]
+    pub fn pipeline_id(&self) -> Option<PipelineId> {
+        self.pipeline_id.get()
+    }
+
+    #[inline]
     pub fn subpage_id(&self) -> Option<SubpageId> {
         self.subpage_id.get()
     }