custom-elements: document.createElement in SVG documents should not create custom elements.

createElement() should assume the namespace is XHTML only if the
document is HTML-like.

New behavior matches to the standard and Firefox.

Bug: 807514
Change-Id: I1164612b6512c94de96bdefbf053e8f132f8b9f7
Reviewed-on: https://chromium-review.googlesource.com/894749
Commit-Queue: Kent Tamura <tkent@chromium.org>
Reviewed-by: Dominic Cooney <dominicc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533221}

third_party/WebKit/LayoutTests/external/wpt/custom-elements/Document-createElement-svg.svg

+<?xml version="1.0" encoding="utf-8"?>
+<svg:svg xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/1999/xhtml"
+   width="100%" height="100%" viewBox="0 0 800 600">
+<svg:title>document.createElement in SVG for custom elements</svg:title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script><![CDATA[
+test(() => {
+  class MyElement1 extends HTMLElement {}
+  customElements.define('my-element', MyElement1);
+  let element = document.createElement('my-element', {});
+  assert_false(element instanceof MyElement1, 'Autonomous custom element should not be created.');
+}, 'document.createElement() in SVG documents should not create autonomous custom elements.')
+
+test(() => {
+  class MyElement2 extends HTMLDivElement {}
+  customElements.define('my-div', MyElement2, { extends: 'div' });
+
+  let element = document.createElement('div', { is: 'my-div' });
+  assert_false(element instanceof MyElement2, 'Custom built-in element should not be created.');
+}, 'document.createElement() in SVG documents should not create custom built-in elements.')
+]]></script>
+</svg:svg>

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

@@ -953,7 +953,13 @@ Element* Document::createElement(const AtomicString& local_name,
 
   // 2. localName converted to ASCII lowercase
   const AtomicString& converted_local_name = ConvertLocalName(local_name);
+  QualifiedName q_name(g_null_atom, converted_local_name,
+                       IsXHTMLDocument() || IsHTMLDocument()
+                           ? HTMLNames::xhtmlNamespaceURI
+                           : g_null_atom);
 
+  // TODO(tkent): Share the code with createElementNS(namespace_uri,
+  // qualified_name, string_or_options, exception_state).
   bool is_v1 = string_or_options.IsDictionary() || !RegistrationContext();
   bool create_v1_builtin =
       string_or_options.IsDictionary() &&
@@ -968,7 +974,7 @@ Element* Document::createElement(const AtomicString& local_name,
 
   // 4. Let definition be result of lookup up custom element definition
   CustomElementDefinition* definition = nullptr;
-  if (is_v1) {
+  if (is_v1 && q_name.NamespaceURI() == HTMLNames::xhtmlNamespaceURI) {
     // Is the runtime flag enabled for customized builtin elements?
     const CustomElementDescriptor desc =
         RuntimeEnabledFeatures::CustomElementsBuiltinEnabled()
@@ -992,20 +998,12 @@ Element* Document::createElement(const AtomicString& local_name,
   Element* element;
 
   if (definition) {
-    element = CustomElement::CreateCustomElementSync(
-        *this, converted_local_name, definition);
+    element = CustomElement::CreateCustomElementSync(*this, q_name, definition);
   } else if (V0CustomElement::IsValidName(local_name) &&
              RegistrationContext()) {
-    element = RegistrationContext()->CreateCustomTagElement(
-        *this,
-        QualifiedName(g_null_atom, converted_local_name, xhtmlNamespaceURI));
+    element = RegistrationContext()->CreateCustomTagElement(*this, q_name);
   } else {
-    element =
-        CreateRawElement(QualifiedName(g_null_atom, converted_local_name,
-                                       IsXHTMLDocument() || IsHTMLDocument()
-                                           ? HTMLNames::xhtmlNamespaceURI
-                                           : g_null_atom),
-                         kCreatedByCreateElement);
+    element = CreateRawElement(q_name, kCreatedByCreateElement);
   }
 
   // 8. If 'is' is non-null, set 'is' attribute

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

@@ -103,16 +103,6 @@ HTMLElement* CustomElement::CreateCustomElementSync(
   return CreateCustomElementSync(document, tag_name, definition);
 }
 
-HTMLElement* CustomElement::CreateCustomElementSync(
-    Document& document,
-    const AtomicString& local_name,
-    CustomElementDefinition* definition) {
-  return CreateCustomElementSync(
-      document,
-      QualifiedName(g_null_atom, local_name, HTMLNames::xhtmlNamespaceURI),
-      definition);
-}
-
 // https://dom.spec.whatwg.org/#concept-create-element
 HTMLElement* CustomElement::CreateCustomElementSync(
     Document& document,

third_party/WebKit/Source/core/html/custom/CustomElement.h

@@ -69,9 +69,6 @@ class CORE_EXPORT CustomElement {
   static bool ShouldCreateCustomizedBuiltinElement(const QualifiedName&);
 
   static HTMLElement* CreateCustomElementSync(Document&, const QualifiedName&);
-  static HTMLElement* CreateCustomElementSync(Document&,
-                                              const AtomicString& local_name,
-                                              CustomElementDefinition*);
   static HTMLElement* CreateCustomElementSync(Document&,
                                               const QualifiedName&,
                                               CustomElementDefinition*);