Avoid unnecessary style recalc for subtree of focused element.

Source/core/dom/ContainerNode.cpp

Index: Source/core/dom/ContainerNode.cpp
diff --git a/Source/core/dom/ContainerNode.cpp b/Source/core/dom/ContainerNode.cpp
index 5664bd9e4f684f44513e6859349ef746e444976c..4d2285f5aee00b9cd026faa5a3e150637e21b7d5 100644
--- a/Source/core/dom/ContainerNode.cpp
+++ b/Source/core/dom/ContainerNode.cpp
@@ -791,6 +791,18 @@ LayoutRect ContainerNode::boundingBox() const
     return enclosingLayoutRect(FloatRect(upperLeft, lowerRight.expandedTo(upperLeft) - upperLeft));
 }
 
+static inline StyleChangeType focusStyleChange(const ContainerNode* node)

[esprehn, 2014/01/22 20:58:52]

This should be a private method, you always pass |this|.

[rune, 2014/01/30 23:24:36]

Done. That is, the method is now gone.

+{
+    // -webkit-user-modify (from contenteditable) needs special propagation (see StyleResolver)
+    // into the shadow dom. Do SubtreeStyleChange even if children are not affected by focus to
+    // cover that.
+    if (node->isElementNode() && (toElement(node)->childrenAffectedByFocus() || toElement(node)->shadow()))

[esprehn, 2014/01/22 20:58:52]

This shadow check doesn't seem right, why do you need to do a subtree recalc if
the thing has a shadow?

[rune, 2014/01/30 17:24:40]

It's about the propagation of -webkit-user-modify for contenteditable into
distributed nodes. I've split out it out as a separate issue[1]/CL with a
different solution[2] and will remove the special casing here.

[1] https://code.google.com/p/chromium/issues/detail?id=339463
[2] https://codereview.chromium.org/144853004/

[rune, 2014/01/30 23:24:36]

Done.

+        return SubtreeStyleChange;
+    if (!node->renderer() || node->renderStyle()->affectedByFocus())
+        return LocalStyleChange;
+    return NoStyleChange;
+}
+
 // This is used by FrameSelection to denote when the active-state of the page has changed
 // independent of the focused element changing.
 void ContainerNode::focusStateChanged()
@@ -799,10 +811,10 @@ void ContainerNode::focusStateChanged()
     // renderer we can just ignore the state change.
     if (!renderer())
         return;
-    // FIXME: This could probably setNeedsStyleRecalc(LocalStyleChange) in the affectedByFocus case
-    // and only setNeedsStyleRecalc(SubtreeStyleChange) in the childrenAffectedByFocus case.
-    if (renderStyle()->affectedByFocus() || (isElementNode() && toElement(this)->childrenAffectedByFocus()))
-        setNeedsStyleRecalc();
+
+    StyleChangeType change = focusStyleChange(this);
+    if (change != NoStyleChange)
+        setNeedsStyleRecalc(change);
     if (renderer() && renderer()->style()->hasAppearance())
         RenderTheme::theme().stateChanged(renderer(), FocusState);
 }
@@ -816,8 +828,10 @@ void ContainerNode::setFocus(bool received)
 
     focusStateChanged();
     // If :focus sets display: none, we lose focus but still need to recalc our style.
-    if (!renderer() && !received)
-        setNeedsStyleRecalc();
+    if (!renderer() && !received) {
+        ASSERT(focusStyleChange(this) != NoStyleChange);
+        setNeedsStyleRecalc(focusStyleChange(this));
+    }
 }
 
 void ContainerNode::setActive(bool down)