[typedarrays] Implement %TypedArray%.prototype.lastIndexOf in C++

src/elements.h

 // Copyright 2012 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.
 
 #ifndef V8_ELEMENTS_H_
 #define V8_ELEMENTS_H_
 
 #include "src/elements-kind.h"
 #include "src/heap/heap.h"
 #include "src/isolate.h"
@@ skipping 153 matching lines @@
                                     Handle<Object> value, uint32_t start,
                                     uint32_t length) = 0;
 
   // Check an Object's own elements for the index of an element (using SameValue
   // semantics)
   virtual Maybe<int64_t> IndexOfValue(Isolate* isolate,
                                       Handle<JSObject> receiver,
                                       Handle<Object> value, uint32_t start,
                                       uint32_t length) = 0;
 
+  virtual Maybe<int64_t> LastIndexOfValue(Isolate* isolate,
+                                          Handle<JSObject> receiver,
+                                          Handle<Object> value,
+                                          uint32_t start) = 0;
+
   virtual void CopyElements(Handle<FixedArrayBase> source,
                             ElementsKind source_kind,
                             Handle<FixedArrayBase> destination, int size) = 0;
 
   virtual Handle<FixedArray> CreateListFromArray(Isolate* isolate,
                                                  Handle<JSArray> array) = 0;
 
  protected:
   friend class LookupIterator;
 
@@ skipping 29 matching lines @@
                      bool allow_appending = false);
 
 MUST_USE_RESULT MaybeHandle<Object> ArrayConstructInitializeElements(
     Handle<JSArray> array,
     Arguments* args);
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_ELEMENTS_H_