[builtins] WIP: Array indexOf in TurboFan/Runtime

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 142 matching lines @@
 
   virtual uint32_t GetCapacity(JSObject* holder,
                                FixedArrayBase* backing_store) = 0;
 
   // Check an Object's own elements for an element (using SameValueZero
   // semantics)
   virtual Maybe<bool> IncludesValue(Isolate* isolate, Handle<JSObject> receiver,
                                     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;
+
  protected:
   friend class LookupIterator;
 
   // Element handlers distinguish between entries and indices when they
   // manipulate elements. Entries refer to elements in terms of their location
   // in the underlying storage's backing store representation, and are between 0
   // and GetCapacity. Indices refer to elements in terms of the value that would
   // be specified in JavaScript to access the element. In most implementations,
   // indices are equivalent to entries. In the NumberDictionary
   // ElementsAccessor, entries are mapped to an index using the KeyAt method on
@@ skipping 22 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_