[Glitch] Change single-column mode to scroll the whole page

Port aa22b38fdb to glitch-soc

Signed-off-by: Thibaut Girka <thib@sitedethib.com>

app/javascript/flavours/glitch/features/public_timeline/index.js

@@ -124,6 +124,7 @@ class PublicTimeline extends React.PureComponent {
           trackScroll={!pinned}
           scrollKey={`public_timeline-${columnId}`}
           emptyMessage={<FormattedMessage id='empty_column.public' defaultMessage='There is nothing here! Write something publicly, or manually follow users from other servers to fill it up' />}
+          bindToDocument={!multiColumn}
         />
       </Column>
     );