[builtins] One runtime fallback is enough for the String constructor.

src/ia32/macro-assembler-ia32.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_IA32_MACRO_ASSEMBLER_IA32_H_
 #define V8_IA32_MACRO_ASSEMBLER_IA32_H_
 
 #include "src/assembler.h"
 #include "src/bailout-reason.h"
 #include "src/frames.h"
@@ skipping 823 matching lines @@
   // from the stack, clobbering only the esp register.
   void Drop(int element_count);
 
   void Call(Label* target) { call(target); }
   void Call(Handle<Code> target, RelocInfo::Mode rmode) { call(target, rmode); }
   void Jump(Handle<Code> target, RelocInfo::Mode rmode) { jmp(target, rmode); }
   void Push(Register src) { push(src); }
   void Push(const Operand& src) { push(src); }
   void Push(Immediate value) { push(value); }
   void Pop(Register dst) { pop(dst); }
+  void Pop(const Operand& dst) { pop(dst); }
   void PushReturnAddressFrom(Register src) { push(src); }
   void PopReturnAddressTo(Register dst) { pop(dst); }
 
   // Non-SSE2 instructions.
   void Pextrd(Register dst, XMMRegister src, int8_t imm8);
   void Pinsrd(XMMRegister dst, Register src, int8_t imm8) {
     Pinsrd(dst, Operand(src), imm8);
   }
   void Pinsrd(XMMRegister dst, const Operand& src, int8_t imm8);
 
@@ skipping 278 matching lines @@
   masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_IA32_MACRO_ASSEMBLER_IA32_H_