Fix newly discovered presubmit errors.

src/x64/lithium-x64.h

 // Copyright 2012 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_X64_LITHIUM_X64_H_
 #define V8_X64_LITHIUM_X64_H_
 
 #include "src/hydrogen.h"
 #include "src/lithium.h"
 #include "src/lithium-allocator.h"
@@ skipping 401 matching lines @@
   }
   int gap_instructions_size() { return gap_instructions_size_; }
 
  private:
   int gap_instructions_size_;
 };
 
 
 class LDummy V8_FINAL : public LTemplateInstruction<1, 0, 0> {
  public:
-  explicit LDummy() { }
+  LDummy() {}
   DECLARE_CONCRETE_INSTRUCTION(Dummy, "dummy")
 };
 
 
 class LDummyUse V8_FINAL : public LTemplateInstruction<1, 1, 0> {
  public:
   explicit LDummyUse(LOperand* value) {
     inputs_[0] = value;
   }
   DECLARE_CONCRETE_INSTRUCTION(DummyUse, "dummy-use")
@@ skipping 2454 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::int
 
 #endif  // V8_X64_LITHIUM_X64_H_