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

test/mjsunit/const-declaration.js

 // 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 151 matching lines @@
     }
     x = 43;  // declare global x
     assertEquals(42, g("x = 42;"));
     x = 44;  // assign to global x
     eval(s);
     x = 45;  // should be ignored (assign to const x)
     assertEquals(0, g("x = 46;"));
   }
   f("const x = 0;");
 })();
-