Iona, Shield of Emeria: no indication of why a color must be chosen when momir'd

When an [Iona](http://magiccards.info/query?q=%21Iona,+Shield+of+Emeria) token is put onto the battlefield using the Momir vanguard's ability, the player who activated it is shown a prompt to choose a color. Clicking the cancel button just opens a new, identical prompt. At this point, the Iona token is not yet displayed on the battlefield, and there is nothing in the game log (shown below chat) to indicate that Iona is entering the battlefield. The chat's text box can also not be accessed at all.

Start by reproducing the Momir Vanguard interaction with an Iona token and trace the color-choice prompt, battlefield display, game log, and chat access described in the report. Done means the prompt explains why a color is required, cancel behaves correctly, Iona's entry is visible in the game log, and the chat text box remains accessible.

Written by the indexing model from the issue text.