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

test/cctest/test-unique.cc

 // 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 528 matching lines @@
       UniqueSet<String>* set2 = MakeSet(&zone, j, elements);
 
       UniqueSet<String>* result = set1->Union(set2, &zone);
       UniqueSet<String>* expected = MakeSet(&zone, i | j, elements);
 
       CHECK(result->Equals(expected));
       CHECK(expected->Equals(result));
     }
   }
 }
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