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

test/mjsunit/regress/regress-990205.js

 // 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 18 matching lines @@
 // (Notice that the example isn't valid ECMAScript due to the
 // function declaration that is not at top level.)
 
 function f() {
   // Force eager compilation of x through the use of eval. The break
   // in function x should not try to break out of the enclosing while.
   return eval("while(0) function x() { break; }; 42");
 };
 
 assertThrows("f()");
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