Open nested submenu on Enter or Space

[web-padawan]

Enter or Space should open nested sub-menu when executed on a parent item, based on the example. Currently, only Arrow Right opens it.

[lkraav]

Apparently this has a side-effect where inputs inside <vaadin-context-menu-item> aren't able to type Space keys.

This is my element configuration, where in <input type="search"> I can only type "Helloworld", not "Hello world":

          <vaadin-tab class="menu-item menu-item-search">
            <a>Search</a> &nbsp;
            <vaadin-context-menu close-on="outside-click" open-on="click" class="sub-menu">
              <template>
                <vaadin-context-menu-item>
                  <form role="search" method="get" id="vaadin-context-menu-search-form" class="search-form" action="https://conversionxl.com/institute/">
                    <label for="s">Search CXL Institute:</label>
                    <div>
                      <input type="search" class="search-field" placeholder="" value="" name="s">
                      <vaadin-button type="submit" class="search-submit" aria-label="Search" theme="icon" onclick="document.getElementById('vaadin-context-menu-search-form').submit();">
                        <iron-icon icon="lumo:angle-right"></iron-icon>
                      </vaadin-button>
                    </div>
                  </form>
                </vaadin-context-menu-item>
              </template>
              <iron-icon icon="lumo:search"></iron-icon> 
            </vaadin-context-menu>
          </vaadin-tab>