Fix crash when removing layout managers.

sky/engine/core/dom/Element.cpp

Index: sky/engine/core/dom/Element.cpp
diff --git a/sky/engine/core/dom/Element.cpp b/sky/engine/core/dom/Element.cpp
index ff0798b1e8f8e33578a31697508606879cc972c9..8537adb6d5e8cd8e4607ab5959d4f2b2b3877168 100644
--- a/sky/engine/core/dom/Element.cpp
+++ b/sky/engine/core/dom/Element.cpp
@@ -964,7 +964,9 @@ LayoutCallback* Element::layoutManager() const
 
 void Element::setLayoutManager(PassOwnPtr<LayoutCallback> callback)
 {
-    if (renderer() && !renderer()->isRenderCustomLayout()) {
+    bool isAlreadyCustomLayout = renderer() && renderer()->isRenderCustomLayout();

[Hixie, 2015/04/14 20:53:38]

Shouldn't this be checking callback != m_layoutManager? If the new layout
manager is the same as the old one, then presumably we don't need to be marked
dirty.

[ojan, 2015/04/14 20:55:05]

Hmmm...this points to a different bug. If the layout managers are different,
then we need to call setNeedsLayout here. Will fix in a followup patch.

+    bool requiresCustomLayout = callback;
+    if (requiresCustomLayout != isAlreadyCustomLayout) {
         // We don't go through the normal reattach codepaths because
         // those are all tied to changes to the RenderStyle.
         markAncestorsWithChildNeedsStyleRecalc();