[RegisterConfiguration] Streamline access to arch defaults, simplify Registers.

src/s390/assembler-s390.h

Index: src/s390/assembler-s390.h
diff --git a/src/s390/assembler-s390.h b/src/s390/assembler-s390.h
index 356c61d2d692cb11254e99a25346cc228989d742..391a5d4aac7ee4c6e056e5153adbb1396005c61c 100644
--- a/src/s390/assembler-s390.h
+++ b/src/s390/assembler-s390.h
@@ -145,9 +145,6 @@ struct Register {
     return r;
   }
 
-  const char* ToString();
-  bool IsAllocatable(RegisterConfiguration::CompilerSelector compiler =
-                         RegisterConfiguration::CRANKSHAFT) const;
   bool is_valid() const { return 0 <= reg_code && reg_code < kNumRegisters; }
   bool is(Register reg) const { return reg_code == reg.reg_code; }
   int code() const {
@@ -203,9 +200,6 @@ struct DoubleRegister {
   static const int kNumRegisters = Code::kAfterLast;
   static const int kMaxNumRegisters = kNumRegisters;
 
-  const char* ToString();
-  bool IsAllocatable(RegisterConfiguration::CompilerSelector compiler =
-                         RegisterConfiguration::CRANKSHAFT) const;
   bool is_valid() const { return 0 <= reg_code && reg_code < kNumRegisters; }
   bool is(DoubleRegister reg) const { return reg_code == reg.reg_code; }