bindings: Skip undefined property descriptors when creating records.

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

 // Copyright (c) 2017 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 NativeValueTraitsImpl_h
 #define NativeValueTraitsImpl_h
 
 #include "bindings/core/v8/IDLTypes.h"
 #include "bindings/core/v8/NativeValueTraits.h"
 #include "bindings/core/v8/V8Binding.h"
@@ skipping 357 matching lines @@
                .ToLocal(&desc)) {
         exceptionState.rethrowV8Exception(block.Exception());
         return ImplType();
       }
 
       // "4.2. If desc is not undefined and desc.[[Enumerable]] is true:"
       // We can call ToLocalChecked() and ToChecked() here because
       // GetOwnPropertyDescriptor is responsible for catching any exceptions
       // and failures, and if we got to this point of the code we have a proper
       // object that was not created by a user.
+      if (desc->IsUndefined())
+        continue;
       DCHECK(desc->IsObject());
       v8::Local<v8::Value> enumerable =
           v8::Local<v8::Object>::Cast(desc)
               ->Get(context, v8String(isolate, "enumerable"))
               .ToLocalChecked();
       if (!enumerable->BooleanValue(context).ToChecked())
         continue;
 
       // "4.2.1. Let typedKey be key converted to an IDL value of type K."
       String typedKey =
@@ skipping 30 matching lines @@
       }
     }
     // "5. Return result."
     return result;
   }
 };
 
 }  // namespace blink
 
 #endif  // NativeValueTraitsImpl_h