Bug 1772562 - Use nsIContent.h for Node in the WebIDL bindings. r=nika

Differential Revision: https://phabricator.services.mozilla.com/D148276

dom/bindings/Bindings.conf

@@ -591,6 +591,11 @@ DOMInterfaces = {
 
 'Node': {
     'nativeType': 'nsINode',
+    # Some WebIDL APIs that return Node use nsIContent internally (which doesn't
+    # have a direct correspondence with any WebIDL interface), so we need to use
+    # nsIContent.h so that the compiler knows nsIContent and nsINode are related
+    # by inheritance.
+    'headerFile': 'nsIContent.h',
 },
 
 'NodeIterator': {