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

src/x64/cpu-x64.cc

 // 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 14 matching lines @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // CPU specific code for x64 independent of OS goes here.
 
 #include "v8.h"
 
 #include "cpu.h"
 #include "macro-assembler.h"
 
-namespace v8 { namespace internal {
+namespace v8 {
+namespace internal {
 
 void CPU::Setup() {
   CpuFeatures::Probe();
 }
 
 
 void CPU::FlushICache(void* start, size_t size) {
   // No need to flush the instruction cache on Intel. On Intel instruction
   // cache flushing is only necessary when multiple cores running the same
   // code simultaneously. V8 (and JavaScript) is single threaded and when code
@@ skipping 10 matching lines @@
   // To avoid Visual Studio runtime support the following code can be used
   // instead
   // __asm { int 3 }
   __debugbreak();
 #else
   asm("int $3");
 #endif
 }
 
 } }  // namespace v8::internal