Equation font size is wrong / canvas size dependent

[keenancrane]

Equation shapes (rendered via MathJax) do not yield the size requested in the fontSize field—the rendered size depends on the canvas size in the Style program. In contrast, Text shapes always get rendered at the proper size, independent of canvas dimensions.

Here's a complete example showing the issue (the Domain schema and Substance program are empty):

canvas {
    width = 10
    height = 8
}

global {
    shape plainText = Text {
        string: "A"
        fillColor: #0a0
        fontSize: "3px"
        fontFamily: "MathJax_Math"
    }
    shape plainTextLabel = Text {
        string: "Text"
        center: plainText.center - (0,1.75)
        fontSize: "1px"
        fillColor: plainText.fillColor
        fontFamily: "monospace"
    }

    shape mathText = Equation {
        string: "A"
        fillColor: #00a
        fontSize: "3px"
    }
    shape mathTextLabel = Text {
        string: "Equation"
        center: mathText.center - (0,3)
        fontSize: "1px"
        fillColor: mathText.fillColor
        fontFamily: "monospace"
    }

    ensure disjoint( mathText, plainText )
}

[wodeni]

To repro this, I also need to download the MathJax_Math font and install it locally:
https://imathas.valenciacollege.edu/mathjax/fonts/HTML-CSS/TeX/otf/