Begin tracking why layout is invalidated

Source/core/layout/LayoutObjectChildList.cpp

Index: Source/core/layout/LayoutObjectChildList.cpp
diff --git a/Source/core/layout/LayoutObjectChildList.cpp b/Source/core/layout/LayoutObjectChildList.cpp
index 4a37b6168f7a3ac4b5186bdd145e01e597719f1f..b5159b233b40d8b481919f215730b387a812a3f1 100644
--- a/Source/core/layout/LayoutObjectChildList.cpp
+++ b/Source/core/layout/LayoutObjectChildList.cpp
@@ -65,7 +65,7 @@ LayoutObject* LayoutObjectChildList::removeChildNode(LayoutObject* owner, Layout
         // that a positioned child got yanked). We also issue paint invalidations, so that the area exposed when the child
         // disappears gets paint invalidated properly.
         if (!owner->documentBeingDestroyed() && notifyRenderer && oldChild->everHadLayout()) {
-            oldChild->setNeedsLayoutAndPrefWidthsRecalc();
+            oldChild->setNeedsLayoutAndPrefWidthsRecalc(LayoutInvalidationReason::DomChanged);

[esprehn, 2015/03/23 20:19:44]

This doesn't mean the dom changed, it could just mean stuff became display none,
or other reasons like the parent decided children were now allowed.

[pdr., 2015/03/24 03:56:19]

Good catch.

I updated this to be "RemovedFromLayout" which isn't the most descriptive name
but I think it will make sense in context.

             invalidatePaintOnRemoval(*oldChild);
         }
     }
@@ -156,7 +156,7 @@ void LayoutObjectChildList::insertChildNode(LayoutObject* owner, LayoutObject* n
         LayoutCounter::rendererSubtreeAttached(newChild);
     }
 
-    newChild->setNeedsLayoutAndPrefWidthsRecalc();
+    newChild->setNeedsLayoutAndPrefWidthsRecalc(LayoutInvalidationReason::DomChanged);

[esprehn, 2015/03/23 20:19:44]

This doesn't mean the dom changed, it could just mean stuff went from display
none -> not none or other reasons.

     newChild->setShouldDoFullPaintInvalidation(PaintInvalidationRendererInsertion);
     if (!owner->normalChildNeedsLayout())
         owner->setChildNeedsLayout(); // We may supply the static position for an absolute positioned child.