Fix missing cases of empty_string canonicalization

src/s390/macro-assembler-s390.h

 // Copyright 2014 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_S390_MACRO_ASSEMBLER_S390_H_
 #define V8_S390_MACRO_ASSEMBLER_S390_H_
 
 #include "src/assembler.h"
 #include "src/bailout-reason.h"
 #include "src/frames.h"
@@ skipping 1769 matching lines @@
 
   void Jump(intptr_t target, RelocInfo::Mode rmode, Condition cond = al,
             CRegister cr = cr7);
 
   // Helper functions for generating invokes.
   void InvokePrologue(const ParameterCount& expected,
                       const ParameterCount& actual, Label* done,
                       bool* definitely_mismatches, InvokeFlag flag,
                       const CallWrapper& call_wrapper);
 
-  void InitializeNewString(Register string, Register length,
-                           Heap::RootListIndex map_index, Register scratch1,
-                           Register scratch2);
-
   // Helper for implementing JumpIfNotInNewSpace and JumpIfInNewSpace.
   void InNewSpace(Register object, Register scratch,
                   Condition cond,  // eq for new space, ne otherwise.
                   Label* branch);
 
   // Helper for finding the mark bits for an address.  Afterwards, the
   // bitmap register points at the word with the mark bits and the mask
   // the position of the first bit.  Leaves addr_reg unchanged.
   inline void GetMarkBits(Register addr_reg, Register bitmap_reg,
                           Register mask_reg);
@@ skipping 49 matching lines @@
 inline MemOperand NativeContextMemOperand() {
   return ContextMemOperand(cp, Context::NATIVE_CONTEXT_INDEX);
 }
 
 #define ACCESS_MASM(masm) masm->
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_S390_MACRO_ASSEMBLER_S390_H_