fix icon default size

Summary:
Logs plugin expected the default icons size to be 16 and therefor didn't set it explicitly. However, with the TS migration we lost the default size.
This adds back the default size for icons.

Reviewed By: jknoxville

Differential Revision: D17156747

fbshipit-source-id: a37f3a2bd189a56019aee1939618caf21122a397

src/ui/components/Glyph.tsx

@@ -87,7 +87,7 @@ export default class Glyph extends React.Component<{
   color?: string;
 }> {
   render() {
-    const {name, size, variant, color, className} = this.props;
+    const {name, size = 16, variant, color, className} = this.props;
 
     return (
       <ColoredIcon