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

src/arm/constants-arm.h

 // Copyright 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_ARM_CONSTANTS_ARM_H_
 #define V8_ARM_CONSTANTS_ARM_H_
 
-namespace assembler { namespace arm {
+namespace assembler {
+namespace arm {
 
 // Defines constants and accessor classes to assemble, disassemble and
 // simulate ARM instructions.
 //
 // Section references in the code refer to the "ARM Architecture Reference
 // Manual" from July 2005 (available at http://www.arm.com/miscPDFs/14128.pdf)
 //
 // Constants for specific fields are defined in their respective named enums.
 // General constants are in an anonymous enum in class Instr.
 
@@ skipping 189 matching lines @@
 
  private:
   // We need to prevent the creation of instances of class Instr.
   DISALLOW_IMPLICIT_CONSTRUCTORS(Instr);
 };
 
 
 } }  // namespace assembler::arm
 
 #endif  // V8_ARM_CONSTANTS_ARM_H_