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

src/arguments.h

 // Copyright 2006-2008 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 10 matching lines @@
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // 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_ARGUMENTS_H_
 #define V8_ARGUMENTS_H_
 
-namespace v8 { namespace internal {
+namespace v8 {
+namespace internal {
 
 // Arguments provides access to runtime call parameters.
 //
 // It uses the fact that the instance fields of Arguments
 // (length_, arguments_) are "overlayed" with the parameters
 // (no. of parameters, and the parameter pointer) passed so
 // that inside the C++ function, the parameters passed can
 // be accessed conveniently:
 //
 //   Object* Runtime_function(Arguments args) {
@@ skipping 19 matching lines @@
   int length() const { return length_; }
 
  private:
   int length_;
   Object** arguments_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARGUMENTS_H_