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

test/mjsunit/regress/regress-2374.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 13 matching lines @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 var msg = '{"result":{"profile":{"head":{"functionName":"(root)","url":"","lineNumber":0,"totalTime":495.7243772462511,"selfTime":0,"numberOfCalls":0,"visible":true,"callUID":2771605942,"children":[{"functionName":"(program)","url":"","lineNumber":0,"totalTime":495.7243772462511,"selfTime":495.7243772462511,"numberOfCalls":0,"visible":true,"callUID":1902715303,"children":[]}]},"bottomUpHead":{"functionName":"(root)","url":"","lineNumber":0,"totalTime":495.7243772462511,"selfTime":0,"numberOfCalls":0,"visible":true,"callUID":2771605942,"children":[{"functionName":"(program)","url":"","lineNumber":0,"totalTime":495.7243772462511,"selfTime":495.7243772462511,"numberOfCalls":0,"visible":true,"callUID":1902715303,"children":[]}]}}},"id":41}';
 
 var obj = JSON.parse(msg);
 var obj2 = JSON.parse(msg);
 
 assertEquals(JSON.stringify(obj), JSON.stringify(obj2));
-assertEquals(JSON.stringify(obj, null, 0), JSON.stringify(obj2));
+assertEquals(JSON.stringify(obj, null, 0), JSON.stringify(obj2));