Refactor common unit test code.

src/compiler/change-lowering-unittest.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/change-lowering.h"
+#include "src/compiler/compiler-test-utils.h"
 #include "src/compiler/graph-unittest.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/node-properties-inl.h"
 #include "src/compiler/simplified-operator.h"
 #include "src/compiler/typer.h"
 #include "testing/gmock-support.h"
 
 using testing::_;
 using testing::AllOf;
 using testing::Capture;
@@ skipping 441 matching lines @@
               IsIfTrue(AllOf(CaptureEq(&branch),
                              IsBranch(IsUint32LessThanOrEqual(
                                           val, IsInt32Constant(SmiMaxValue())),
                                       graph()->start()))),
               AllOf(CaptureEq(&if_false), IsIfFalse(CaptureEq(&branch))))));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8