[presubmit] Enable readability/namespace linter checking.

src/x87/assembler-x87-inl.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 // - Redistributions of source code must retain the above copyright notice,
 // this list of conditions and the following disclaimer.
 //
@@ skipping 536 matching lines @@
   set_modrm(0, ebp);
   set_dispr(disp, rmode);
 }
 
 
 Operand::Operand(Immediate imm) {
   // [disp/r]
   set_modrm(0, ebp);
   set_dispr(imm.x_, imm.rmode_);
 }
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_X87_ASSEMBLER_X87_INL_H_