Bug 1827856 - Improve docs of IsInSameAnonymousTree. r=smaug

Depends on D175353

Differential Revision: https://phabricator.services.mozilla.com/D175354

dom/base/nsContentUtils.cpp

@@ -5793,23 +5793,23 @@ bool nsContentUtils::HasNonEmptyTextContent(
 
 /* static */
 bool nsContentUtils::IsInSameAnonymousTree(const nsINode* aNode,
-                                           const nsIContent* aContent) {
+                                           const nsINode* aOtherNode) {
   MOZ_ASSERT(aNode, "Must have a node to work with");
-  MOZ_ASSERT(aContent, "Must have a content to work with");
+  MOZ_ASSERT(aOtherNode, "Must have a content to work with");
 
-  if (aNode->IsInNativeAnonymousSubtree() !=
-      aContent->IsInNativeAnonymousSubtree()) {
+  const bool anon = aNode->IsInNativeAnonymousSubtree();
+  if (anon != aOtherNode->IsInNativeAnonymousSubtree()) {
     return false;
   }
 
-  if (aNode->IsInNativeAnonymousSubtree()) {
-    return aContent->GetClosestNativeAnonymousSubtreeRoot() ==
+  if (anon) {
+    return aOtherNode->GetClosestNativeAnonymousSubtreeRoot() ==
            aNode->GetClosestNativeAnonymousSubtreeRoot();
   }
 
   // FIXME: This doesn't deal with disconnected nodes whatsoever, but it didn't
   // use to either. Maybe that's fine.
-  return aNode->GetContainingShadow() == aContent->GetContainingShadow();
+  return aNode->GetContainingShadow() == aOtherNode->GetContainingShadow();
 }
 
 /* static */

dom/base/nsContentUtils.h

@@ -1118,11 +1118,8 @@ class nsContentUtils {
   static bool IsInPrivateBrowsing(nsILoadGroup* aLoadGroup);
 
   /**
-   * If aNode is not an element, return true exactly when aContent's binding
-   * parent is null.
-   *
-   * If aNode is an element, return true exactly when aContent's binding parent
-   * is the same as aNode's.
+   * Returns whether a node is in the same tree as another one, accounting for
+   * anonymous roots.
    *
    * This method is particularly useful for callers who are trying to ensure
    * that they are working with a non-anonymous descendant of a given node.  If
@@ -1132,7 +1129,7 @@ class nsContentUtils {
    * Both arguments to this method must be non-null.
    */
   static bool IsInSameAnonymousTree(const nsINode* aNode,
-                                    const nsIContent* aContent);
+                                    const nsINode* aOtherNode);
 
   /*
    * Traverse the parent chain from aElement up to aStop, and return true if