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

src/mips64/deoptimizer-mips64.cc

Index: src/mips64/deoptimizer-mips64.cc
diff --git a/src/mips64/deoptimizer-mips64.cc b/src/mips64/deoptimizer-mips64.cc
index 90bd11e5e300dc6237164d7523370d8861ac29f1..ea17124c63ee66503897a8967445de3b45524ccf 100644
--- a/src/mips64/deoptimizer-mips64.cc
+++ b/src/mips64/deoptimizer-mips64.cc
@@ -117,8 +117,7 @@ void Deoptimizer::TableEntryGenerator::Generate() {
 
   // Save all FPU registers before messing with them.
   __ Dsubu(sp, sp, Operand(kDoubleRegsSize));
-  const RegisterConfiguration* config =
-      RegisterConfiguration::ArchDefault(RegisterConfiguration::CRANKSHAFT);
+  const RegisterConfiguration* config = RegisterConfiguration::Crankshaft();
   for (int i = 0; i < config->num_allocatable_double_registers(); ++i) {
     int code = config->GetAllocatableDoubleCode(i);
     const DoubleRegister fpu_reg = DoubleRegister::from_code(code);