Set undefined when calling a %TypedArray%.indexOf withtout arguments

src/builtins/builtins-typedarray.cc

 // Copyright 2016 the V8 project 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 "src/builtins/builtins-utils.h"
 #include "src/builtins/builtins.h"
 #include "src/code-stub-assembler.h"
 #include "src/counters.h"
 #include "src/elements.h"
 #include "src/objects-inl.h"
@@ skipping 527 matching lines @@
   if (args.length() > 2) {
     Handle<Object> num;
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
         isolate, num, Object::ToInteger(isolate, args.at<Object>(2)));
     index = CapRelativeIndex(num, 0, len);
   }
 
   // TODO(cwhan.tunz): throw. See the above comment in CopyWithin.
   if (V8_UNLIKELY(array->WasNeutered())) return isolate->heap()->false_value();
 
-  Handle<Object> search_element = args.at<Object>(1);
+  Handle<Object> search_element = args.atOrUndefined(isolate, 1);
   ElementsAccessor* elements = array->GetElementsAccessor();
   Maybe<bool> result = elements->IncludesValue(isolate, array, search_element,
                                                static_cast<uint32_t>(index),
                                                static_cast<uint32_t>(len));
   MAYBE_RETURN(result, isolate->heap()->exception());
   return *isolate->factory()->ToBoolean(result.FromJust());
 }
 
 BUILTIN(TypedArrayPrototypeIndexOf) {
   HandleScope scope(isolate);
@@ skipping 10 matching lines @@
   if (args.length() > 2) {
     Handle<Object> num;
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
         isolate, num, Object::ToInteger(isolate, args.at<Object>(2)));
     index = CapRelativeIndex(num, 0, len);
   }
 
   // TODO(cwhan.tunz): throw. See the above comment in CopyWithin.
   if (V8_UNLIKELY(array->WasNeutered())) return Smi::FromInt(-1);
 
-  Handle<Object> search_element = args.at<Object>(1);
+  Handle<Object> search_element = args.atOrUndefined(isolate, 1);
   ElementsAccessor* elements = array->GetElementsAccessor();
   Maybe<int64_t> result = elements->IndexOfValue(isolate, array, search_element,
                                                  static_cast<uint32_t>(index),
                                                  static_cast<uint32_t>(len));
   MAYBE_RETURN(result, isolate->heap()->exception());
   return *isolate->factory()->NewNumberFromInt64(result.FromJust());
 }
 
 }  // namespace internal
 }  // namespace v8