Implement "create an element" when sync for Custom Element V1

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

Index: third_party/WebKit/Source/core/dom/custom/CustomElementDefinition.cpp
diff --git a/third_party/WebKit/Source/core/dom/custom/CustomElementDefinition.cpp b/third_party/WebKit/Source/core/dom/custom/CustomElementDefinition.cpp
index b261c80514f8de4966a4f07f43eb41362d471fe0..b19de7c9f60594bdda98063f4ed6a9d18062fdbe 100644
--- a/third_party/WebKit/Source/core/dom/custom/CustomElementDefinition.cpp
+++ b/third_party/WebKit/Source/core/dom/custom/CustomElementDefinition.cpp
@@ -4,6 +4,8 @@
 
 #include "core/dom/custom/CustomElementDefinition.h"
 
+#include "core/dom/ExceptionCode.h"
+
 namespace blink {
 
 CustomElementDefinition::CustomElementDefinition(
@@ -46,4 +48,47 @@ void CustomElementDefinition::upgrade(Element* element)
     CHECK(element->getCustomElementState() == CustomElementState::Custom);
 }
 
+static String errorMessageForConstructorResult(Element* element,
+    Document& document, const QualifiedName& tagName)
+{
+    // https://dom.spec.whatwg.org/#concept-create-element
+    // 6.1.4. If result's attribute list is not empty, then throw a NotSupportedError.
+    if (element->hasAttributes())
+        return "The result must not have attributes";
+    // 6.1.5. If result has children, then throw a NotSupportedError.
+    if (element->hasChildren())
+        return "The result must not have children";
+    // 6.1.6. If result's parent is not null, then throw a NotSupportedError.
+    if (element->parentNode())
+        return "The result must not have a parent";
+    // 6.1.7. If result's node document is not document, then throw a NotSupportedError.
+    if (&element->document() != &document)
+        return "The result must be in the same document";
+    // 6.1.8. If result's namespace is not the HTML namespace, then throw a NotSupportedError.
+    if (element->namespaceURI() != HTMLNames::xhtmlNamespaceURI)
+        return "The result must have HTML namespace";
+    // 6.1.9. If result's local name is not equal to localName, then throw a NotSupportedError.
+    if (element->localName() != tagName.localName())
+        return "The result must have the same localName";
+    return String();
+}
+
+void CustomElementDefinition::errorForConstructorResult(Element* element,
+    Document& document, const QualifiedName& tagName,
+    ExceptionState& exceptionState)
+{
+    // https://dom.spec.whatwg.org/#concept-create-element
+    // 6.1.3. If result does not implement the HTMLElement interface, throw a TypeError.
+    // See https://github.com/whatwg/html/issues/1402 for more clarifications.
+    if (!element || !element->isHTMLElement()) {
+        exceptionState.throwTypeError("The result must implement HTMLElement interface");
+        return;
+    }
+
+    // 6.1.4. through 6.1.9.
+    const String message = errorMessageForConstructorResult(element, document, tagName);
+    if (!message.isEmpty())
+        exceptionState.throwDOMException(NotSupportedError, message);
+}
+
 } // namespace blink