Ext component trees are not initialized in the same order in all browsers

Each Ext component tree is initialized in an Ext.onReady() callback. Each callback should directly be triggered by an explicit call to Ext.fireDocReady() after it. However, it turns out that not all browsers execute these onReady callbacks in the same order. Chrome executes all callbacks in the order they appear in the response, but in Firefox and IE the order usually differs. Ext code that relies on global changes done by components in another component tree may therefore break in Firefox and IE.