Link hints: don't show hints for spans which have clickable descendants

This is to remove the false hints that are shown on Google's search result pages, especially on tabs
other than the main "All" tab. See #4303 and #4750.

Author: philc

content_scripts/link_hints.js

@@ -1243,6 +1243,12 @@ const LocalHints = {
       possibleFalsePositive = true;
     }
 
+    // If the span is clickable but wraps something else that is clickable, we want to instead favor
+    // showing hints for descendants which are clickable. Flag the span as a possible false postive.
+    if (tagName == "span") {
+      possibleFalsePositive = true;
+    }
+
     // Elements with tabindex are sometimes useful, but usually not. We can treat them as second
     // class citizens when it improves UX, so take special note of them.
     const tabIndexValue = element.getAttribute("tabindex");