remove dodgy heuristics for hiding dates on RRs and use DateUtils instead.

reverts https://github.com/matrix-org/matrix-react-sdk/pull/586/commits/5d99d68a64ec0c81b42c5a8e6959376dab798feb
fixes https://github.com/vector-im/riot-web/issues/3523

src/components/views/rooms/EventTile.js

@@ -295,16 +295,6 @@ module.exports = WithMatrixClient(React.createClass({
         const receiptOffset = 15;
         let left = 0;
 
-        // It's possible that the receipt was sent several days AFTER the event.
-        // If it is, we want to display the complete date along with the HH:MM:SS,
-        // rather than just HH:MM:SS.
-        let dayAfterEvent = new Date(this.props.mxEvent.getTs());
-        dayAfterEvent.setDate(dayAfterEvent.getDate() + 1);
-        dayAfterEvent.setHours(0);
-        dayAfterEvent.setMinutes(0);
-        dayAfterEvent.setSeconds(0);
-        let dayAfterEventTime = dayAfterEvent.getTime();
-
         var receipts = this.props.readReceipts || [];
         for (var i = 0; i < receipts.length; ++i) {
             var receipt = receipts[i];
@@ -340,7 +330,6 @@ module.exports = WithMatrixClient(React.createClass({
                     suppressAnimation={this._suppressReadReceiptAnimation}
                     onClick={this.toggleAllReadAvatars}
                     timestamp={receipt.ts}
-                    showFullTimestamp={receipt.ts >= dayAfterEventTime}
                 />
             );
         }