Make sure files end with exactly one new line and police this in presubmit.

test/mjsunit/never-optimize.js

 // Copyright 2013 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 42 matching lines @@
 
   %OptimizeFunctionOnNextCall(u1);
   %OptimizeFunctionOnNextCall(u2);
 
   u1(); u1();
   u2(); u2();
 
   // 2 => not optimized.
   assertUnoptimized(u1);
   assertOptimized(u2);
-}
+}