symbol layout 'icon-size' < 0.1 is treated as 0

[zoltan-mihalyi]

mapbox-gl-js version: 0.47.0

browser: chrome, firefox

Steps to Trigger Behavior

1. create symbol layer with 'icon-size' as expression (not constant)
2. make sure the expression evaluates to 0.09

Link to Demonstration

https://jsfiddle.net/og5tbcLn/31/

In the demonstration, there is two features with size 0.1 and 0.09 calculated from property.
The icon with size 0.1 is displayed while the 0.09 is not.

If i set 'icon-size': 0.09 (not expression) it works as expected.
It also works as expected if the expression does not contain ['get', ...] expression

Expected Behavior

Display the symbol with 0.09 scale

Actual Behavior

Symbol is displayed with 0 scale