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

src/crankshaft/mips/lithium-codegen-mips.cc

Index: src/crankshaft/mips/lithium-codegen-mips.cc
diff --git a/src/crankshaft/mips/lithium-codegen-mips.cc b/src/crankshaft/mips/lithium-codegen-mips.cc
index 7e659ea29eba5107ac8c144bca047f1b93926642..30a59fcc198a6b26f060a7d59988bc3ab4e3ed94 100644
--- a/src/crankshaft/mips/lithium-codegen-mips.cc
+++ b/src/crankshaft/mips/lithium-codegen-mips.cc
@@ -3534,7 +3534,9 @@ void LCodeGen::PrepareForTailCall(const ParameterCount& actual,
 #endif
   if (FLAG_code_comments) {
     if (actual.is_reg()) {
-      Comment(";;; PrepareForTailCall, actual: %s {", actual.reg().ToString());
+      Comment(";;; PrepareForTailCall, actual: %s {",
+              RegisterConfiguration::Crankshaft()->GetGeneralRegisterName(
+                  actual.reg().code()));
     } else {
       Comment(";;; PrepareForTailCall, actual: %d {", actual.immediate());
     }