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

src/crankshaft/ia32/lithium-codegen-ia32.cc

Index: src/crankshaft/ia32/lithium-codegen-ia32.cc
diff --git a/src/crankshaft/ia32/lithium-codegen-ia32.cc b/src/crankshaft/ia32/lithium-codegen-ia32.cc
index 4cad5b61bd6d5c93ed1736192b4cf204f8220a0f..e4854e70d5877614c424d5ed59cce8523f232029 100644
--- a/src/crankshaft/ia32/lithium-codegen-ia32.cc
+++ b/src/crankshaft/ia32/lithium-codegen-ia32.cc
@@ -3474,7 +3474,9 @@ 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());
     }