popover_menus: Fix popovers not shown if reference is beside compose.

Since `#compose` occupies full width of the window, it is a
part of `elements_at_reference_position` if the reference is
under it.

Since `#compose-content` only occupies the part of window where
compose box is actually visible, we use it decide if the
popover should be hidden.

web/src/popover_menus.js

@@ -210,7 +210,7 @@ export const default_popover_props = {
                         elements_at_reference_position.some(
                             (element) =>
                                 element.id === "navbar-fixed-container" ||
-                                element.id === "compose" ||
+                                element.id === "compose-content" ||
                                 element.classList.contains("sticky_header"),
                         )
                     ) {