Revert "Add shortcut key for Browser Restart command"

Revert "[suggestion] Main menu - Restart normally (improvements)" (note: poor commit message!)
This reverts commit c0f9a92de8d0d158a901af2b0310a821e5250c70.
This resolves #1490.

browser/base/content/browser-appmenu.inc

@@ -188,8 +188,7 @@
       <menuitem id="appmenu_restart"
                 class="menuitem-iconic"
                 label="&appMenuRestart.label;"
-                command="cmd_restartApplication"
-                key="key_restartApplication"/>
+                command="cmd_restartApplication"/>
       <menuitem id="appmenu-quit"
                 class="menuitem-iconic"
 #ifdef XP_WIN

browser/base/content/browser-menubar.inc

@@ -87,7 +87,6 @@
                 <menuitem id="menu_restart"
                           label="&appMenuRestart.label;"
                           accesskey="&appMenuRestart.accesskey;"
-                          key="key_restartApplication"
                           command="cmd_restartApplication"/>
                 <menuitem id="menu_FileQuitItem"
 #ifdef XP_WIN

browser/base/content/browser-sets.inc

@@ -397,7 +397,6 @@
 
     <key id="key_privatebrowsing" command="Tools:PrivateBrowsing" key="&privateBrowsingCmd.commandkey;" modifiers="accel,shift"/>
     <key id="key_sanitize" command="Tools:Sanitize" keycode="VK_DELETE" modifiers="accel,shift"/>
-    <key id="key_restartApplication" key="&appMenuRestartCmd.commandkey;" command="cmd_restartApplication" modifiers="accel,alt"/>
 #ifdef XP_MACOSX
     <key id="key_sanitize_mac" command="Tools:Sanitize" keycode="VK_BACK" modifiers="accel,shift"/>
 #endif

browser/locales/en-US/chrome/browser/browser.dtd

@@ -550,7 +550,6 @@ you can use these alternative items. Otherwise, their values should be empty.  -
 
 <!ENTITY appMenuRestart.label           "Restart">
 <!ENTITY appMenuRestart.accesskey       "R">
-<!ENTITY appMenuRestartCmd.commandkey   "R">
 
 <!ENTITY quitApplicationCmdWin.label       "Exit"> 
 <!ENTITY quitApplicationCmdWin.accesskey   "x">