Re-reland: Remove register index/code indirection

test/unittests/compiler/register-allocator-unittest.cc

Index: test/unittests/compiler/register-allocator-unittest.cc
diff --git a/test/unittests/compiler/register-allocator-unittest.cc b/test/unittests/compiler/register-allocator-unittest.cc
index 75942b6854b9a6c60d1a619d7cee34ff07e9e5ae..c5ff90f301ec2ecc6165c57d997412b0a2adbe14 100644
--- a/test/unittests/compiler/register-allocator-unittest.cc
+++ b/test/unittests/compiler/register-allocator-unittest.cc
@@ -41,7 +41,8 @@ bool AllocatedOperandMatches(
     const AllocatedOperand& op,
     const InstructionSequenceTest::TestOperand& test_op) {
   return AreOperandsOfSameType(op, test_op) &&
-         (op.index() == test_op.value_ ||
+         ((op.IsRegister() ? op.GetRegister().code() : op.index()) ==
+              test_op.value_ ||
           test_op.value_ == InstructionSequenceTest::kNoValue);
 }