[WebUI] Cancel/OK order in donottrack overlay reversed

Settings overlays are generally cancel/OK, donottrack was OK/cancel.

BUG=425141
R=dbeam@chromium.org

Review URL: https://codereview.chromium.org/665113003

Cr-Commit-Position: refs/heads/master@{#300305}

chrome/browser/resources/options/do_not_track_confirm_overlay.html

@@ -14,13 +14,13 @@
     </div>
     <div class="action-area-right">
       <div class="button-strip">
-        <button id="do-not-track-confirm-ok" class="default-button"
-            i18n-content="doNotTrackConfirmEnable">
-        </button>
         <button id="do-not-track-confirm-cancel"
             i18n-content="doNotTrackConfirmDisable"
             class="cancel-button">
         </button>
+        <button id="do-not-track-confirm-ok" class="default-button"
+            i18n-content="doNotTrackConfirmEnable">
+        </button>
       </div>
     </div>
   </div>