X87: [builtins] One runtime fallback is enough for the String constructor.

src/x87/macro-assembler-x87.h

Index: src/x87/macro-assembler-x87.h
diff --git a/src/x87/macro-assembler-x87.h b/src/x87/macro-assembler-x87.h
index 4535f8f9f463e13196c09642f18789e295cef078..a1464c57a3d591dc03c3339297ea3c3601459e27 100644
--- a/src/x87/macro-assembler-x87.h
+++ b/src/x87/macro-assembler-x87.h
@@ -804,6 +804,7 @@ class MacroAssembler: public Assembler {
   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); }