Set undefined when calling %TypedArray%.indexOf without arguments

Set undefined to the first argument (search element) if the first
argument is not given in %TypedArray%.prototype.indexOf or
%TypedArray%.prototype.includes

BUG=chromium:700894

Review-Url: https://codereview.chromium.org/2748113002
Cr-Commit-Position: refs/heads/master@{#43794}

src/builtins/builtins-typedarray.cc

@@ -700,7 +700,7 @@ BUILTIN(TypedArrayPrototypeIncludes) {
   // 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),
@@ -731,7 +731,7 @@ BUILTIN(TypedArrayPrototypeIndexOf) {
   // 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),