Split nested namespaces declaration in two lines in accordance with C++ Style Guide.

src/x64/assembler-x64-inl.h

 // Copyright 2009 the V8 project authors. 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.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 12 matching lines @@
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #ifndef V8_X64_ASSEMBLER_X64_INL_H_
 #define V8_X64_ASSEMBLER_X64_INL_H_
 
 #include "cpu.h"
 
-namespace v8 { namespace internal {
+namespace v8 {
+namespace internal {
 
 Condition NegateCondition(Condition cc) {
   return static_cast<Condition>(cc ^ 1);
 }
 
 
 // -----------------------------------------------------------------------------
 // Implementation of Assembler
 
 #define EMIT(x)                                 \
@@ skipping 154 matching lines @@
 
 
 Operand::Operand(Register reg) {
   // reg
   set_modrm(3, reg);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_ASSEMBLER_X64_INL_H_