Bug 1637908 - Move the clickableAncestor computation further down. r=snorp

There's a few early-return conditions where we don't need to do this computation
at all. So this patch just moves the computation to after the early-returns. No
functional changes intended.

Differential Revision: https://phabricator.services.mozilla.com/D91025

layout/base/PositionedEventTargeting.cpp

@@ -446,18 +446,6 @@ nsIFrame* FindFrameTargetedByInputEvent(
     PET_LOG("Retargeting disabled\n");
     return target;
   }
-  nsIContent* clickableAncestor = nullptr;
-  if (target) {
-    clickableAncestor = GetClickableAncestor(target, nsGkAtoms::body);
-    if (clickableAncestor) {
-      PET_LOG("Target %p is clickable\n", target);
-      // If the target that was directly hit has a clickable ancestor, that
-      // means it too is clickable. And since it is the same as or a descendant
-      // of clickableAncestor, it should become the root for the GetClosest
-      // search.
-      clickableAncestor = target->GetContent();
-    }
-  }
 
   // Do not modify targeting for actual mouse hardware; only for mouse
   // events generated by touch-screen hardware.
@@ -487,6 +475,19 @@ nsIFrame* FindFrameTargetedByInputEvent(
     return target;
   }
 
+  nsIContent* clickableAncestor = nullptr;
+  if (target) {
+    clickableAncestor = GetClickableAncestor(target, nsGkAtoms::body);
+    if (clickableAncestor) {
+      PET_LOG("Target %p is clickable\n", target);
+      // If the target that was directly hit has a clickable ancestor, that
+      // means it too is clickable. And since it is the same as or a descendant
+      // of clickableAncestor, it should become the root for the GetClosest
+      // search.
+      clickableAncestor = target->GetContent();
+    }
+  }
+
   nsIFrame* closestClickable =
       GetClosest(aRootFrame, aPointRelativeToRootFrame, targetRect, prefs,
                  restrictToDescendants, clickableAncestor, candidates);