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

test/mjsunit/eval-stack-trace.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 183 matching lines @@
   //   f (eval at <anonymous> (test.js:182:40), <anonymous>:2:9)
   //   test.js:186:3
   var frames = e.getFrames();
   assertEquals(2, frames.length);
   ["f"].verifyEquals(frames, "getFunctionName");
   [2].verifyEquals(frames, "getLineNumber");
   ["<anonymous>:2:"].verifyContains(frames, "toString");
   [true, false].verifyUndefined(frames, "getFileName");
   ["eval at <anonymous> ("].verifyContains(frames, "getEvalOrigin");
 }
-