[HaTS] Remove scroll style fix

The scroll style fix was due to a bug introduced from cl/270089435.
Now they already fixed the bug in HaTS library code, so we can remove
this hack.

BUG=none

Change-Id: I832dd33a10ad2091ae19e422e4f512b490af5fe4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1880817Reviewed-by: Dan Beam <dbeam@chromium.org>
Commit-Queue: Wei Li <weili@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709670}

chrome/browser/resources/hats/hats.html

@@ -16,13 +16,6 @@
         /* Needs to override dynamically loaded, more specific styles. */
         outline-color: rgb(77, 144, 254) !important;
       }
-      /* Make sure scroll bars are added only when necessary, the overriden
-       * value is 'scroll' which causes scroll bars always show.
-       * TODO(weili): Remove this once the overriden value changed to auto.
-       */
-      #t402-prompt.t402-prompt-websat-modal {
-        overflow: auto !important;
-      }
     </style>
     <script>
       /**