Introduce CustomElementRegistry#get() method

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/dom/custom/CustomElementsRegistry.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ScriptCustomElementDefinitionBuilder.h"
 #include "core/dom/Document.h"
 #include "core/dom/ElementRegistrationOptions.h"
@@ skipping 94 matching lines @@
     CHECK(!exceptionState.hadException());
     CHECK(definition->descriptor() == descriptor);
     DefinitionMap::AddResult result =
         m_definitions.add(descriptor.name(), definition);
     CHECK(result.isNewEntry);
 
     // TODO(dominicc): Implement steps:
     // 20: when-defined promise processing
 }
 
+// https://html.spec.whatwg.org/multipage/scripting.html#dom-customelementsregistry-get
+ScriptValue CustomElementsRegistry::get(
+    ScriptState* scriptState,
+    const AtomicString& name)
+{
+    CustomElementDefinition* definition = definitionForName(name);
+    if (!definition) {
+        // Binding layer converts |ScriptValue()| to script specific value,

[dominicc (has gone to gerrit), 2016/05/31 22:56:32]

Love this comment. Short and specific.

+        // e.g. |undefined| for v8.
+        return ScriptValue();
+    }
+    return definition->getConstructor(scriptState);
+}
+
 bool CustomElementsRegistry::v0NameIsDefined(const AtomicString& name) const
 {
     if (!m_v0)
         return false;
     return m_v0->nameIsDefined(name);
 }
 
 CustomElementDefinition* CustomElementsRegistry::definitionForName(
     const AtomicString& name) const
 {
     return m_definitions.get(name);
 }
 
 } // namespace blink