<mspace linebreak="newline" /> not working.

[henok-tesfaye]

Issue Summary

<mspace linebreak="newline" /> not working tried it in Mathjax demo page.

<math xmlns="http://www.w3.org/1998/Math/MathML">
    <mi>H</mi>
    <mi>o</mi>
    <mi>r</mi>
    <mi>i</mi>
    <mi>z</mi>
    <mi>o</mi>
    <mi>n</mi>
    <mi>t</mi>
    <mi>a</mi>
    <mi>l</mi>
    <mo></mo>
    <mi>a</mi>
    <mi>s</mi>
    <mi>y</mi>
    <mi>m</mi>
    <mi>p</mi>
    <mi>t</mi>
    <mi>o</mi>
    <mi>t</mi>
    <mi>e</mi>
    <mfenced>
        <mi>s</mi>
    </mfenced>
    <mo>=</mo>
    <mrow>
        <mrow>
            <mfenced close="}" open="{">
                <mrow>
                    <mi>y</mi>
                    <mo>=</mo>
                    <mn>0</mn>
                    <mo>.</mo>
                    <mn>750</mn>
                </mrow>
            </mfenced>
        </mrow>
    </mrow>
    <mspace linebreak="newline"/>
    <mi>V</mi>
    <mi>e</mi>
    <mi>r</mi>
    <mi>t</mi>
    <mi>i</mi>
    <mi>c</mi>
    <mi>a</mi>
    <mi>l</mi>
    <mo></mo>
    <mi>a</mi>
    <mi>s</mi>
    <mi>y</mi>
    <mi>m</mi>
    <mi>p</mi>
    <mi>t</mi>
    <mi>o</mi>
    <mi>t</mi>
    <mi>e</mi>
    <mfenced>
        <mi>s</mi>
    </mfenced>
    <mo>=</mo>
    <mrow>
        <mrow>
            <mfenced close="}" open="{">
                <mrow>
                    <mi>x</mi>
                    <mo>=</mo>
                    <mo>-</mo>
                    <mn>3</mn>
                    <mo>.</mo>
                    <mn>000</mn>
                    <mo>,</mo>
                    <mi>x</mi>
                    <mo>=</mo>
                    <mn>1</mn>
                    <mo>.</mo>
                    <mn>250</mn>
                </mrow>
            </mfenced>
        </mrow>
    </mrow>
</math>

Steps to Reproduce:

1. Open https://www.mathjax.org/#demo
2. Go to live demo section
3. Copy paste the above snippet

Expected Behavior: Vertical Asymptote text should be displayed in a new line

Technical details:

• MathJax Version: 2.3 (latest commit: f3aaf3a)
• Client OS: Mac OS X 10.14.6
• Browser: Chrome 84.0.4147.105 (Official Build) (64-bit)

[dpvc]

Line breaking is not yet implemented in v3 (some v2 features are still being ported).

This is a duplicate of #2312 (and #2382, #2418, and #2491).

[chrispitude]

How's this feature coming along (for MathML rendering)?

[dpvc]

@chrispitude, It is scheduled for second-quarter next year.

[chrispitude]

Thanks @dpvc!

[dpvc]

Closing as a duplicate.