Add icon in comments to be able to preview it

[lukaskurz]

Would be cool, if we could use the same logic that the inbuilt material icons use to display the icon in the autocomplete feature of the IDE.

/// <i class="material-icons-round md-36">timer_off</i> &#x2014; material icon named "timer off" (round).
static const IconData timer_off_rounded = IconData(0xf023b, fontFamily: 'MaterialIcons');

/// <i class="material-icons-outlined md-36">timer_off</i> &#x2014; material icon named "timer off" (outlined).
static const IconData timer_off_outlined = IconData(0xf449, fontFamily: 'MaterialIcons');

/// <i class="material-icons md-36">tips_and_updates</i> &#x2014; material icon named "tips and updates".
static const IconData tips_and_updates = IconData(0xf058d, fontFamily: 'MaterialIcons');

Like this: