binding: Supports V8PrivateProperty::getOrUndefined.

third_party/WebKit/Source/bindings/core/v8/V8PrivateProperty.h

 // 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.
 
 #ifndef V8PrivateProperty_h
 #define V8PrivateProperty_h
 
 #include "bindings/core/v8/ScopedPersistent.h"
 #include "bindings/core/v8/ScriptPromiseProperties.h"
 #include "bindings/core/v8/V8BindingMacros.h"
@@ skipping 54 matching lines @@
     // expensive compared to get or set a private property.  This class
     // provides a way to cache a private symbol and re-use it.
     class CORE_EXPORT Symbol {
         STACK_ALLOCATED();
     public:
         bool hasValue(v8::Local<v8::Context> context, v8::Local<v8::Object> object) const
         {
             return v8CallBoolean(object->HasPrivate(context, m_privateSymbol));
         }
 
+        // Returns the value of the private property if set, or undefined.
+        v8::Local<v8::Value> getOrUndefined(v8::Local<v8::Context> context, v8::Local<v8::Object> object) const
+        {
+            return v8CallOrCrash(object->GetPrivate(context, m_privateSymbol));
+        }
+
+        // Returns the value of the private property if set, or an empty handle.
         v8::Local<v8::Value> get(v8::Local<v8::Context> context, v8::Local<v8::Object> object) const
         {
             if (!v8CallBoolean(object->HasPrivate(context, m_privateSymbol)))
                 return v8::Local<v8::Value>();
             v8::Local<v8::Value> value;
             if (v8Call(object->GetPrivate(context, m_privateSymbol), value))
                 return value;
             return v8::Local<v8::Value>();
         }
 
@@ skipping 51 matching lines @@
 
 #define V8_PRIVATE_PROPERTY_DECLARE_MEMBER(InterfaceName, KeyName) \
     ScopedPersistent<v8::Private> V8_PRIVATE_PROPERTY_MEMBER_NAME(InterfaceName, KeyName); // NOLINT(readability/naming/underscores)
     V8_PRIVATE_PROPERTY_FOR_EACH(V8_PRIVATE_PROPERTY_DECLARE_MEMBER)
 #undef V8_PRIVATE_PROPERTY_DECLARE_MEMBER
 };
 
 } // namespace blink
 
 #endif // V8PrivateProperty_h