Call Element::rebuildLayoutTree from Document::updateStyle directly

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

Index: third_party/WebKit/Source/core/dom/Node.cpp
diff --git a/third_party/WebKit/Source/core/dom/Node.cpp b/third_party/WebKit/Source/core/dom/Node.cpp
index d5feaa1f73d247f0c0df0b1925e500de1d7eb700..d4fb79c7f893da24326c8ce258083b8ad1103614 100644
--- a/third_party/WebKit/Source/core/dom/Node.cpp
+++ b/third_party/WebKit/Source/core/dom/Node.cpp
@@ -913,6 +913,7 @@ void Node::detachLayoutTree(const AttachContext& context) {
     layoutObject()->destroyAndCleanupAnonymousWrappers();
   setLayoutObject(nullptr);
   setStyleChange(NeedsReattachStyleChange);
+  setLocalNeedsReattachLayoutTree();

[nainar, 2016/12/07 14:48:21]

make sure that we are setting the NeedsReattachLayoutTree flag on each node that
we set NeedsReattachStyleChange information on. 

[Bugs Nash, 2016/12/07 23:21:44]

this function is difficult to understand at first glance. shouldn't this be
calling setNeedsReattachLayoutTree() so that the ancestors are marked too?
alternatively if you're not setting it cause you can guarantee it will be
immediately attached after this then setting the NeedsReattachLayoutTree flag
shouldn't be necessary

[nainar, 2016/12/07 23:49:10]

As per discussion with esprehn@, we want to set the NeedsReattachLayoutTree flag
only on the node itself and check that wherever we set the
NeedsReattachStyleChange flag to make sure that we attach all nodes that need it
and then clear the bits correctly.

The line directly above also doesn't call Node::setNeedsStyleRecalc() with the
NeedsReattachStyleChange flag (which would amongst other things set the
childNeedsStyleRecalc flag on the ancestors) but instead only sets the flag on
the node itself.

[Bugs Nash, 2016/12/08 00:27:59]

If this is similar to the above call then I would recommend naming it similarly.
It's not clear what 'local' means here.

[nainar, 2016/12/08 00:45:48]

Yup that makes sense calling setFlag(NeedsReattachLayoutTree) directly here
instead of that. Made the change locally. 

   clearChildNeedsStyleInvalidation();
 }