ios: Assert if closing keyboard and touching the screen with another finger

To reproduce:

• run attached example
• press TextField
• slide down the keyboard until it disappears and keep holding the finger on screen
• touch somewhere on screen with another finger

This output is printed:

QPlatformInputContext::inputMethodAccepted() does not match actual focus object IM enablement!
ASSERT: "m_context->isInputPanelVisible()" in file qiosinputcontext.mm, line 213