Prevent unwanted forced inline breaks in SVG semantics elements. (mathjax/MathJax#3428)

[dpvc]

This PR prevents the temporarily forced line breaks used for making potential line breaks in SVG in-line expressions from always causing line breaks. The semantics element doesn't have an inferred mrow, so it was missed when looking through its children for the proper breakpoint element.

Resolves issue mathjax/MathJax#3428.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.71%. Comparing base (afaf1ea) to head (20a5452).

Files with missing lines	Patch %	Lines
ts/output/common/Wrapper.ts	0.00%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1346      +/-   ##
===========================================
- Coverage    86.72%   86.71%   -0.01%     
===========================================
  Files          337      337              
  Lines        84145    84146       +1     
  Branches      3140     4769    +1629     
===========================================
  Hits         72971    72971              
+ Misses       11174    11152      -22     
- Partials         0       23      +23     

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