Allow <link rel=stylesheet> in a connected shadow tree

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

Index: third_party/WebKit/Source/core/dom/StyleSheetCandidate.cpp
diff --git a/third_party/WebKit/Source/core/dom/StyleSheetCandidate.cpp b/third_party/WebKit/Source/core/dom/StyleSheetCandidate.cpp
index 2ffe72b632cb27050fec4286cc4342278e7971e8..c5335b0e526a072c5e5e452d38a894ecaf2bd856 100644
--- a/third_party/WebKit/Source/core/dom/StyleSheetCandidate.cpp
+++ b/third_party/WebKit/Source/core/dom/StyleSheetCandidate.cpp
@@ -88,8 +88,10 @@ bool StyleSheetCandidate::canBeActivated(const String& currentPreferrableName) c
     if (!sheet || sheet->disabled() || !sheet->isCSSStyleSheet())
         return false;
 
-    if (sheet->ownerNode() && sheet->ownerNode()->isInShadowTree())
-        return true;
+    if (sheet->ownerNode() && sheet->ownerNode()->isInShadowTree()) {
+        if (isCSSStyle() || (isHTMLLink() && !isImport() && !isAlternate()))

[kochi, 2016/07/29 07:10:12]

I'm not sure !isImport() here makes sense.

My understanding is that if isHTMLLink() is true, it is already
<link rel="stylesheet" ...>
so does |&& !isImport()| check mean
<link rel="stylesheet import" ...>
?

[hayato, 2016/07/29 07:41:56]

I think we should check, as far as I see:

-
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/dom/Style...
-
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/dom/Style...

+            return true;
+    }
 
     const AtomicString& title = this->title();
     if (!isEnabledViaScript() && !title.isEmpty() && title != currentPreferrableName)