MIPS: Reland of `Fix bad RegisterConfiguration usage in InstructionSequence unit tests`

test/unittests/compiler/instruction-sequence-unittest.cc

Index: test/unittests/compiler/instruction-sequence-unittest.cc
diff --git a/test/unittests/compiler/instruction-sequence-unittest.cc b/test/unittests/compiler/instruction-sequence-unittest.cc
index e61f690b4ef29adbb8bd2d0f6306fe9582be7020..ee9f7914a63e32631d92c7a64852c1810ee4f104 100644
--- a/test/unittests/compiler/instruction-sequence-unittest.cc
+++ b/test/unittests/compiler/instruction-sequence-unittest.cc
@@ -85,7 +85,7 @@ int InstructionSequenceTest::GetAllocatableCode(int index,
   }
 }
 
-RegisterConfiguration* InstructionSequenceTest::config() {
+const RegisterConfiguration* InstructionSequenceTest::config() {
   if (!config_) {
     config_.reset(new RegisterConfiguration(
         num_general_registers_, num_double_registers_, num_general_registers_,
@@ -105,6 +105,8 @@ InstructionSequence* InstructionSequenceTest::sequence() {
   if (sequence_ == nullptr) {
     sequence_ = new (zone())
         InstructionSequence(isolate(), zone(), &instruction_blocks_);
+    sequence_->SetRegisterConfigurationForTesting(
+        InstructionSequenceTest::config());
   }
   return sequence_;
 }