Move some helper methods to DexRegisterLocation.

Test: test-art-host-gtest-stack_map_test
Change-Id: I0abab008159db023d531df69214cd3bb8c0639bd
diff --git a/runtime/check_reference_map_visitor.h b/runtime/check_reference_map_visitor.h
index 8a2a70e..8f9f45c 100644
--- a/runtime/check_reference_map_visitor.h
+++ b/runtime/check_reference_map_visitor.h
@@ -75,7 +75,7 @@
     for (int i = 0; i < number_of_references; ++i) {
       int reg = registers[i];
       CHECK_LT(reg, accessor.RegistersSize());
-      DexRegisterLocation location = dex_register_map.GetDexRegisterLocation(reg);
+      DexRegisterLocation location = dex_register_map[reg];
       switch (location.GetKind()) {
         case DexRegisterLocation::Kind::kNone:
           // Not set, should not be a reference.
@@ -98,7 +98,7 @@
           CHECK_EQ(location.GetValue(), 0);
           break;
         default:
-          LOG(FATAL) << "Unexpected location kind " << location.GetInternalKind();
+          LOG(FATAL) << "Unexpected location kind " << location.GetKind();
       }
     }
   }