Handle closed mode shadow for /deep/ and ::shadow selectors

Source/core/css/resolver/SharedStyleFinder.cpp

Index: Source/core/css/resolver/SharedStyleFinder.cpp
diff --git a/Source/core/css/resolver/SharedStyleFinder.cpp b/Source/core/css/resolver/SharedStyleFinder.cpp
index 198ac8fcf60f06ad1825b02a425d0bf71c7a8977..8bee74f26697bbc567fb0fe408b0f8666b558224 100644
--- a/Source/core/css/resolver/SharedStyleFinder.cpp
+++ b/Source/core/css/resolver/SharedStyleFinder.cpp
@@ -266,6 +266,11 @@ bool SharedStyleFinder::canShareStyleWithElement(Element& candidate) const
             return false;
     }
 
+    ShadowRoot* root1 = element().containingShadowRoot();

[hayato, 2015/08/19 05:45:24]

Could you explain why we need this check briefly?

[kochi, 2015/08/19 07:33:54]

Previously we assumed that when 2 nodes under parents that share styles in
common
can share the style (see line 209), which breaks the following case:

<div>
  #shadow-root(open)
    <div#div1>
<div>
  #shadow-root(closed)
    <div#div2>

[hayato, 2015/08/20 03:47:11]

Acknowledged.

+    ShadowRoot* root2 = candidate.containingShadowRoot();
+    if (root1 && root2 && root1->type() != root2->type())
+        return false;
+
     if (document().containsValidityStyleRules()) {
         if (candidate.isValidElement() != element().isValidElement())
             return false;