add id to print item; r=kin; bug #43904

editor/ui/composer/content/editorOverlay.xul

@@ -282,7 +282,7 @@
       <menuseparator />
       <menuitem accesskey="&fileprintsetup.accesskey;"                           observes="cmd_printSetup" />
       <menuitem accesskey="&fileprintpreview.accesskey;"                         observes="cmd_printPreview"/>
-      <menuitem accesskey="&fileprint.accesskey;"           key="printkb"        observes="cmd_print" value="&printCmd.label;"/>
+      <menuitem accesskey="&fileprint.accesskey;" id="printMenuItem" key="printkb" observes="cmd_print" value="&printCmd.label;"/>
       <menuseparator />
       <menuitem accesskey="&fileexit.accesskey;"            key="exitkb"         observes="cmd_quit"/>
     </menupopup>