Fix InputElement#blurOnEscape

[willeastcott]

Looks like a copy and paste error.

[slimbuck]

Might fix playcanvas/editor#1008 ?

[willeastcott]

It's possible. But I'm almost certain it fixes the chat widget, where when you hit enter, the text input element loses focus, despite being declared like this:

    const input = new TextInput({
        blurOnEnter: false,
        keyChange: true,
        placeholder: '>'
    });

This bug surfaced after I ported the chat widget to PCUI a few months back.