[turbofan] Implement JSBuiltinReducer for String.prototype[Symbol.iterator].

src/objects.h

 // Copyright 2015 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_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 #include <memory>
 
@@ skipping 7218 matching lines @@
   kGlobalEncodeURI,
   kGlobalEncodeURIComponent,
   kGlobalEscape,
   kGlobalUnescape,
   kGlobalIsFinite,
   kGlobalIsNaN,
   kTypedArrayByteLength,
   kTypedArrayByteOffset,
   kTypedArrayLength,
   kSharedArrayBufferByteLength,
+  kStringIterator,
   kStringIteratorNext,
 };
 
 
 // Result of searching in an optimized code map of a SharedFunctionInfo. Note
 // that both {code} and {literals} can be NULL to pass search result status.
 struct CodeAndLiterals {
   Code* code;            // Cached optimized code.
   LiteralsArray* literals;  // Cached literals array.
 };
@@ skipping 4360 matching lines @@
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_