[LayoutNG] Remove unneeded comments in a test

This patch removes a comment in a test that is not needed. It
was a left over in r615053 (CL:1366472).

Bug: 904291
Change-Id: I785080fd401426261d6259c22f5f20059fdcba1f
Reviewed-on: https://chromium-review.googlesource.com/c/1370148Reviewed-by: Christian Biesinger <cbiesinger@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615473}

third_party/blink/web_tests/fast/text/absolute-in-inline-block-change-crash.html

@@ -10,7 +10,6 @@ if (window.testRunner)
   testRunner.dumpAsText();
 
 document.body.offsetTop;
-//abs.appendChild(document.createTextNode('abs'));
 abs.style.top = '0';
 </script>
 </body>