Make Custom Elements V1 work in HTML imports documents

third_party/WebKit/Source/core/dom/custom/CustomElement.cpp

Index: third_party/WebKit/Source/core/dom/custom/CustomElement.cpp
diff --git a/third_party/WebKit/Source/core/dom/custom/CustomElement.cpp b/third_party/WebKit/Source/core/dom/custom/CustomElement.cpp
index bab2bec31f979861f122309a32330b8eedf6d6be..57061b3d7e5af5c49d6b11ad9ac13fae50d45391 100644
--- a/third_party/WebKit/Source/core/dom/custom/CustomElement.cpp
+++ b/third_party/WebKit/Source/core/dom/custom/CustomElement.cpp
@@ -27,8 +27,17 @@ CustomElementsRegistry* CustomElement::registry(const Element& element)
 
 CustomElementsRegistry* CustomElement::registry(const Document& document)
 {
-    if (LocalDOMWindow* window = document.domWindow())
-        return window->customElements();
+    if (Document* contextDocument = const_cast<Document&>(document).contextDocument()) {
+        if (LocalDOMWindow* window = contextDocument->domWindow())
+            return window->customElements();
+    }
+    return nullptr;
+}
+
+FrameHost* CustomElement::contextFrameHost(const Element& element)
+{
+    if (Document* contextDocument = element.document().contextDocument())
+        return contextDocument->frameHost();
     return nullptr;
 }
 
@@ -78,7 +87,8 @@ bool CustomElement::isValidName(const AtomicString& name)
 bool CustomElement::shouldCreateCustomElement(Document& document, const AtomicString& localName)
 {
     return RuntimeEnabledFeatures::customElementsV1Enabled()
-        && document.frame() && isValidName(localName);
+        && document.contextDocument() && document.contextDocument()->frame()
+        && isValidName(localName);
 }
 
 bool CustomElement::shouldCreateCustomElement(Document& document, const QualifiedName& tagName)
@@ -176,7 +186,7 @@ void CustomElement::enqueue(Element* element, CustomElementReaction* reaction)
 
     // If the custom element reactions stack is empty, then
     // Add element to the backup element queue.
-    element->document().frameHost()->customElementReactionStack()
+    contextFrameHost(*element)->customElementReactionStack()
         .enqueueToBackupQueue(element, reaction);
 }