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

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 f1e231cb1aa15fc374b15bd984f335d3c4c34276..83d82d902f7e2f2e8a23ceab9852528288271a42 100644
--- a/third_party/WebKit/Source/core/dom/custom/CustomElement.cpp
+++ b/third_party/WebKit/Source/core/dom/custom/CustomElement.cpp
@@ -86,8 +86,28 @@ HTMLElement* CustomElement::createCustomElement(Document& document, const Atomic
         flags);
 }
 
+HTMLElement* CustomElement::createCustomElement(Document& document, const AtomicString& localName, CreateElementFlags flags,
+    ExceptionState& exceptionState)
+{
+    return createCustomElement(document,
+        QualifiedName(nullAtom, localName, HTMLNames::xhtmlNamespaceURI),
+        flags, exceptionState);
+}
+
 HTMLElement* CustomElement::createCustomElement(Document& document, const QualifiedName& tagName, CreateElementFlags flags)
 {
+    return createCustomElement(document, tagName, flags, nullptr);
+}
+
+HTMLElement* CustomElement::createCustomElement(Document& document, const QualifiedName& tagName, CreateElementFlags flags,
+    ExceptionState& exceptionState)
+{
+    return createCustomElement(document, tagName, flags, &exceptionState);
+}
+
+HTMLElement* CustomElement::createCustomElement(Document& document, const QualifiedName& tagName, CreateElementFlags flags,
+    ExceptionState* exceptionState)
+{
     DCHECK(shouldCreateCustomElement(document, tagName));
 
     // To create an element:
@@ -100,7 +120,16 @@ HTMLElement* CustomElement::createCustomElement(Document& document, const Qualif
             if (flags & AsynchronousCustomElements)
                 return createCustomElementAsync(document, *definition, tagName);
 
-            // TODO(kojii): Synchronous mode implementation coming after async.
+            // When invoked from "create an element for a token":
+            // https://html.spec.whatwg.org/multipage/syntax.html#create-an-element-for-the-token
+            // 7. If this step throws an exception, then report the exception,
+            // and let element be instead a new element that implements
+            // HTMLUnknownElement.
+            if (!exceptionState)
+                return definition->createElementByRunningConstructor(document, tagName);
+
+            // 6.1. If the synchronous custom elements flag is set:
+            return definition->createElementByRunningConstructor(document, tagName, *exceptionState);
         }
     }