Revert of Internalize strings in-place

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"
@@ skipping 694 matching lines @@
   // 2^32−1, inclusive.
   // ES#sec-touint32
   compiler::Node* ToUint32(compiler::Node* context, compiler::Node* input);
 
   // Convert any object to a String.
   Node* ToString(Node* context, Node* input);
 
   // Convert any object to a Primitive.
   Node* JSReceiverToPrimitive(Node* context, Node* input);
 
+  // Convert a String to a flat String.
+  Node* FlattenString(Node* string);
+
   enum ToIntegerTruncationMode {
     kNoTruncation,
     kTruncateMinusZero,
   };
 
   // Convert any object to an Integer.
   Node* ToInteger(Node* context, Node* input,
                   ToIntegerTruncationMode mode = kNoTruncation);
 
   // Returns a node that contains a decoded (unsigned!) value of a bit
@@ skipping 83 matching lines @@
   void Increment(Variable& variable, int value = 1,
                  ParameterMode mode = INTPTR_PARAMETERS);
 
   // Generates "if (false) goto label" code. Useful for marking a label as
   // "live" to avoid assertion failures during graph building. In the resulting
   // code this check will be eliminated.
   void Use(Label* label);
 
   // Various building blocks for stubs doing property lookups.
   void TryToName(Node* key, Label* if_keyisindex, Variable* var_index,
-                 Label* if_keyisunique, Variable* var_unique,
-                 Label* if_bailout);
+                 Label* if_keyisunique, Label* if_bailout);
 
   // Calculates array index for given dictionary entry and entry field.
   // See Dictionary::EntryToIndex().
   template <typename Dictionary>
   Node* EntryToIndex(Node* entry, int field_index);
   template <typename Dictionary>
   Node* EntryToIndex(Node* entry) {
     return EntryToIndex<Dictionary>(entry, Dictionary::kEntryKeyIndex);
   }
   // Calculate a valid size for the a hash table.
@@ skipping 420 matching lines @@
   }
 #else
 #define CSA_SLOW_ASSERT(csa, x) ((void)0)
 #endif
 
 DEFINE_OPERATORS_FOR_FLAGS(CodeStubAssembler::AllocationFlags);
 
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_CODE_STUB_ASSEMBLER_H_