[turbofan] Merge compiler unit tests into src.

test/compiler-unittests/common-operator-unittest.h

-// 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.
-
-#ifndef V8_COMPILER_UNITTESTS_COMMON_OPERATOR_UNITTEST_H_
-#define V8_COMPILER_UNITTESTS_COMMON_OPERATOR_UNITTEST_H_
-
-#include "src/compiler/common-operator.h"
-#include "test/compiler-unittests/compiler-unittests.h"
-
-namespace v8 {
-namespace internal {
-namespace compiler {
-
-class CommonOperatorTest : public CompilerTest {
- public:
-  CommonOperatorTest();
-  virtual ~CommonOperatorTest();
-
- protected:
-  CommonOperatorBuilder* common() { return &common_; }
-
- private:
-  CommonOperatorBuilder common_;
-};
-
-}  // namespace compiler
-}  // namespace internal
-}  // namespace v8
-
-#endif  // V8_COMPILER_UNITTESTS_COMMON_OPERATOR_UNITTEST_H_