Reschedule sibling invalidations as descendant on removal.

third_party/WebKit/Source/core/dom/Document.cpp

Index: third_party/WebKit/Source/core/dom/Document.cpp
diff --git a/third_party/WebKit/Source/core/dom/Document.cpp b/third_party/WebKit/Source/core/dom/Document.cpp
index 196ca5cf71e0922c4c43e48707f68464262b6511..6b23f4f015beeb1def67394e74e9d18c28ccd985 100644
--- a/third_party/WebKit/Source/core/dom/Document.cpp
+++ b/third_party/WebKit/Source/core/dom/Document.cpp
@@ -4218,6 +4218,9 @@ void Document::nodeWillBeRemoved(Node& n) {
 
   if (containsV1ShadowTree())
     n.checkSlotChangeBeforeRemoved();
+
+  if (n.inActiveDocument() && n.isElementNode())
+    styleEngine().elementWillBeRemoved(toElement(n));

[esprehn, 2016/12/22 17:19:59]

Hooking here is unusual, we'd normally do Element::removed from and pass the
parent node into the thing. We should figure out how to reconcile the code here
and the code there. :/

[rune, 2016/12/23 00:06:37]

You were thinking along the lines of having a willBeRemovedFrom in Node along
insertedInto and removedFrom? And have the implementation on Element call
StyleEngine to reschedule its invalidation set?

 }
 
 void Document::dataWillChange(const CharacterData& characterData) {