Revert of [turbofan] inline %StringIteratorPrototype%.next in JSBuiltinReducer.

src/code-stub-assembler.h

 // 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.
 
 #ifndef V8_CODE_STUB_ASSEMBLER_H_
 #define V8_CODE_STUB_ASSEMBLER_H_
 
 #include <functional>
 
 #include "src/compiler/code-assembler.h"
 #include "src/objects.h"
 
 namespace v8 {
 namespace internal {
 
 class CallInterfaceDescriptor;
 class StatsCounter;
 class StubCache;
 
 enum class PrimitiveType { kBoolean, kNumber, kString, kSymbol };
 
+enum class UnicodeEncoding {
+  // Different unicode encodings in a |word32|:
+  UTF16,  // hi 16bits -> trailing surrogate or 0, low 16bits -> lead surrogate
+  UTF32,  // full UTF32 code unit / Unicode codepoint
+};
+
 #define HEAP_CONSTANT_LIST(V)                 \
   V(BooleanMap, BooleanMap)                   \
   V(empty_string, EmptyString)                \
   V(EmptyFixedArray, EmptyFixedArray)         \
   V(FixedArrayMap, FixedArrayMap)             \
   V(FixedCOWArrayMap, FixedCOWArrayMap)       \
   V(FixedDoubleArrayMap, FixedDoubleArrayMap) \
   V(HeapNumberMap, HeapNumberMap)             \
   V(MinusZeroValue, MinusZero)                \
   V(NanValue, Nan)                            \
@@ skipping 859 matching lines @@
                                            Label* bailout);
 
   static const int kElementLoopUnrollThreshold = 8;
 };
 
 DEFINE_OPERATORS_FOR_FLAGS(CodeStubAssembler::AllocationFlags);
 
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_CODE_STUB_ASSEMBLER_H_