Make custom elements work in HTML imports

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 282fa462f1cec75149c5b5725d8acbb0f682adb5..736513fb7040e1cdb7afa26a6f588a634de3e694 100644
--- a/third_party/WebKit/Source/core/dom/custom/CustomElement.cpp
+++ b/third_party/WebKit/Source/core/dom/custom/CustomElement.cpp
@@ -24,10 +24,13 @@ CustomElementsRegistry* CustomElement::registry(const Element& element)
 {
     return registry(element.document());
 }
+
 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;
 }
 
@@ -81,6 +84,7 @@ bool CustomElement::isValidName(const AtomicString& name)
 bool CustomElement::shouldCreateCustomElement(Document& document, const AtomicString& localName)
 {
     return RuntimeEnabledFeatures::customElementsV1Enabled()
+        && document.contextDocument() && document.contextDocument()->frame()
         && isValidName(localName);
 }