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

test/mjsunit/regress/regress-131994.js

 // Copyright 2012 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 49 matching lines @@
     var x = 3;  // Allocated in the local scope.
     debugger;  // Break.
   };
 
   f();
 }
 
 h();
 
 assertFalse(exception);
-