Bug 1813980: Check IsDoc before Parent in RemoteAccessibleBase::ApplyCrossDocOffset. r=morgan

We call this function on every ancestor when calculating bounds.
RemoteParent() currently requires a hash lookup, so it's more efficient to early return for !IsDoc() first.
This is a micro-optimisation, but it might have some impact given that we call this on every ancestor, especially when hit testing, where we call Bounds() a lot.

As a bit of drive-by cleanup, use RemoteParent() rather than calling Parent() and IsRemote/AsRemote().

Differential Revision: https://phabricator.services.mozilla.com/D168346

accessible/ipc/RemoteAccessibleBase.cpp

@@ -464,19 +464,19 @@ Maybe<nsRect> RemoteAccessibleBase<Derived>::RetrieveCachedBounds() const {
 
 template <class Derived>
 void RemoteAccessibleBase<Derived>::ApplyCrossDocOffset(nsRect& aBounds) const {
-  Accessible* parentAcc = Parent();
-  if (!parentAcc || !parentAcc->IsRemote() || !parentAcc->IsOuterDoc()) {
-    return;
-  }
-
   if (!IsDoc()) {
     // We should only apply cross-doc offsets to documents. If we're anything
     // else, return early here.
     return;
   }
 
+  RemoteAccessible* parentAcc = RemoteParent();
+  if (!parentAcc || !parentAcc->IsOuterDoc()) {
+    return;
+  }
+
   Maybe<const nsTArray<int32_t>&> maybeOffset =
-      parentAcc->AsRemote()->mCachedFields->GetAttribute<nsTArray<int32_t>>(
+      parentAcc->mCachedFields->GetAttribute<nsTArray<int32_t>>(
           nsGkAtoms::crossorigin);
   if (!maybeOffset) {
     return;