[presubmit] Enable readability/namespace linter checking.

src/compiler/arm64/instruction-codes-arm64.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_ARM64_INSTRUCTION_CODES_ARM64_H_
 #define V8_COMPILER_ARM64_INSTRUCTION_CODES_ARM64_H_
 
 namespace v8 {
 namespace internal {
 namespace compiler {
@@ skipping 140 matching lines @@
   V(MRR)              /* [%r0 + %r1] */                         \
   V(Operand2_R_LSL_I) /* %r0 LSL K */                           \
   V(Operand2_R_LSR_I) /* %r0 LSR K */                           \
   V(Operand2_R_ASR_I) /* %r0 ASR K */                           \
   V(Operand2_R_ROR_I) /* %r0 ROR K */                           \
   V(Operand2_R_UXTB)  /* %r0 UXTB (unsigned extend byte) */     \
   V(Operand2_R_UXTH)  /* %r0 UXTH (unsigned extend halfword) */ \
   V(Operand2_R_SXTB)  /* %r0 SXTB (signed extend byte) */       \
   V(Operand2_R_SXTH)  /* %r0 SXTH (signed extend halfword) */
 
+}  // namespace compiler
 }  // namespace internal
-}  // namespace compiler
 }  // namespace v8
 
 #endif  // V8_COMPILER_ARM64_INSTRUCTION_CODES_ARM64_H_