--- a/dom/base/nsINode.cpp
+++ b/dom/base/nsINode.cpp
@@ -1168,17 +1168,17 @@ nsPIDOMWindowOuter* nsINode::GetOwnerGlo
 nsIGlobalObject* nsINode::GetOwnerGlobal() const {
   bool dummy;
   return OwnerDoc()->GetScriptHandlingObject(dummy);
 }
 
 bool nsINode::UnoptimizableCCNode() const {
   const uintptr_t problematicFlags =
       (NODE_IS_ANONYMOUS_ROOT | NODE_IS_IN_NATIVE_ANONYMOUS_SUBTREE |
-       NODE_IS_NATIVE_ANONYMOUS_ROOT | NODE_MAY_BE_IN_BINDING_MNGR);
+       NODE_IS_NATIVE_ANONYMOUS_ROOT);
   return HasFlag(problematicFlags) || NodeType() == ATTRIBUTE_NODE ||
          // For strange cases like xbl:content/xbl:children
          (IsElement() && AsElement()->IsInNamespace(kNameSpaceID_XBL));
 }
 
 /* static */
 bool nsINode::Traverse(nsINode* tmp, nsCycleCollectionTraversalCallback& cb) {
   if (MOZ_LIKELY(!cb.WantAllTraces())) {

--- a/dom/base/nsINode.h
+++ b/dom/base/nsINode.h
@@ -126,74 +126,69 @@ enum {
   NODE_IS_IN_NATIVE_ANONYMOUS_SUBTREE = NODE_FLAG_BIT(3),
 
   // Whether this node is the root of a native anonymous (from the perspective
   // of its parent) subtree.  This flag is set-once: once a node has it, it
   // must not be removed.
   // NOTE: Should only be used on nsIContent nodes
   NODE_IS_NATIVE_ANONYMOUS_ROOT = NODE_FLAG_BIT(4),
 
-  // Whether a binding manager may have a pointer to this
-  NODE_MAY_BE_IN_BINDING_MNGR = NODE_FLAG_BIT(5),
-
-  NODE_IS_EDITABLE = NODE_FLAG_BIT(6),
-
-  // Free bit here.
+  NODE_IS_EDITABLE = NODE_FLAG_BIT(5),
 
   // Whether the node participates in a shadow tree.
-  NODE_IS_IN_SHADOW_TREE = NODE_FLAG_BIT(8),
+  NODE_IS_IN_SHADOW_TREE = NODE_FLAG_BIT(6),
 
   // Node has an :empty or :-moz-only-whitespace selector
-  NODE_HAS_EMPTY_SELECTOR = NODE_FLAG_BIT(9),
+  NODE_HAS_EMPTY_SELECTOR = NODE_FLAG_BIT(7),
 
   // A child of the node has a selector such that any insertion,
   // removal, or appending of children requires restyling the parent.
-  NODE_HAS_SLOW_SELECTOR = NODE_FLAG_BIT(10),
+  NODE_HAS_SLOW_SELECTOR = NODE_FLAG_BIT(8),
 
   // A child of the node has a :first-child, :-moz-first-node,
   // :only-child, :last-child or :-moz-last-node selector.
-  NODE_HAS_EDGE_CHILD_SELECTOR = NODE_FLAG_BIT(11),
+  NODE_HAS_EDGE_CHILD_SELECTOR = NODE_FLAG_BIT(9),
 
   // A child of the node has a selector such that any insertion or
   // removal of children requires restyling later siblings of that
   // element.  Additionally (in this manner it is stronger than
   // NODE_HAS_SLOW_SELECTOR), if a child's style changes due to any
   // other content tree changes (e.g., the child changes to or from
   // matching :empty due to a grandchild insertion or removal), the
   // child's later siblings must also be restyled.
-  NODE_HAS_SLOW_SELECTOR_LATER_SIBLINGS = NODE_FLAG_BIT(12),
+  NODE_HAS_SLOW_SELECTOR_LATER_SIBLINGS = NODE_FLAG_BIT(10),
 
   NODE_ALL_SELECTOR_FLAGS = NODE_HAS_EMPTY_SELECTOR | NODE_HAS_SLOW_SELECTOR |
                             NODE_HAS_EDGE_CHILD_SELECTOR |
                             NODE_HAS_SLOW_SELECTOR_LATER_SIBLINGS,
 
   // This node needs to go through frame construction to get a frame (or
   // undisplayed entry).
-  NODE_NEEDS_FRAME = NODE_FLAG_BIT(13),
+  NODE_NEEDS_FRAME = NODE_FLAG_BIT(11),
 
   // At least one descendant in the flattened tree has NODE_NEEDS_FRAME set.
   // This should be set on every node on the flattened tree path between the
   // node(s) with NODE_NEEDS_FRAME and the root content.
-  NODE_DESCENDANTS_NEED_FRAMES = NODE_FLAG_BIT(14),
+  NODE_DESCENDANTS_NEED_FRAMES = NODE_FLAG_BIT(12),
 
   // Set if the node has the accesskey attribute set.
-  NODE_HAS_ACCESSKEY = NODE_FLAG_BIT(15),
+  NODE_HAS_ACCESSKEY = NODE_FLAG_BIT(13),
 
   // Set if the node has right-to-left directionality
-  NODE_HAS_DIRECTION_RTL = NODE_FLAG_BIT(16),
+  NODE_HAS_DIRECTION_RTL = NODE_FLAG_BIT(14),
 
   // Set if the node has left-to-right directionality
-  NODE_HAS_DIRECTION_LTR = NODE_FLAG_BIT(17),
+  NODE_HAS_DIRECTION_LTR = NODE_FLAG_BIT(15),
 
   NODE_ALL_DIRECTION_FLAGS = NODE_HAS_DIRECTION_LTR | NODE_HAS_DIRECTION_RTL,
 
-  NODE_HAS_BEEN_IN_UA_WIDGET = NODE_FLAG_BIT(18),
+  NODE_HAS_BEEN_IN_UA_WIDGET = NODE_FLAG_BIT(16),
 
   // Remaining bits are node type specific.
-  NODE_TYPE_SPECIFIC_BITS_OFFSET = 19
+  NODE_TYPE_SPECIFIC_BITS_OFFSET = 17
 };
 
 // Make sure we have space for our bits
 #define ASSERT_NODE_FLAGS_SPACE(n)                         \
   static_assert(WRAPPER_CACHE_FLAGS_BITS_USED + (n) <=     \
                     sizeof(nsWrapperCache::FlagsType) * 8, \
                 "Not enough space for our bits")
 ASSERT_NODE_FLAGS_SPACE(NODE_TYPE_SPECIFIC_BITS_OFFSET);

--- a/servo/components/style/gecko/wrapper.rs
+++ b/servo/components/style/gecko/wrapper.rs
@@ -295,17 +295,17 @@ impl<'ln> GeckoNode<'ln> {
     }
 
     /// WARNING: This logic is duplicated in Gecko's FlattenedTreeParentIsParent.
     /// Make sure to mirror any modifications in both places.
     #[inline]
     fn flattened_tree_parent_is_parent(&self) -> bool {
         use crate::gecko_bindings::structs::*;
         let flags = self.flags();
-        if flags & (NODE_MAY_BE_IN_BINDING_MNGR as u32 | NODE_IS_IN_SHADOW_TREE as u32) != 0 {
+        if !self.is_in_shadow_tree() {
             return false;
         }
 
         let parent = unsafe { self.0.mParent.as_ref() }.map(GeckoNode);
         let parent_el = parent.and_then(|p| p.as_element());
         if flags & (NODE_IS_NATIVE_ANONYMOUS_ROOT as u32) != 0 &&
             parent_el.map_or(false, |el| el.is_root())
         {