Ignore degenerate touch spans when scaling

[calixteman]

Math.hypot(...) || 1 turned a zero span into one pixel and produced an artificial scale ratio. Skip near-zero spans and test recovery on the next move.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.10%. Comparing base (7364bca) to head (9cedb4e).

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #21741   +/-   ##
=======================================
  Coverage   90.09%   90.10%           
=======================================
  Files         264      264           
  Lines       67234    67235    +1     
=======================================
+ Hits        60574    60580    +6     
+ Misses       6660     6655    -5     

Flag	Coverage Δ
browsertest	66.34% <33.33%> (-0.01%)	⬇️
fonttest	8.99% <ø> (ø)
integrationtest	69.31% <100.00%> (+0.01%)	⬆️
unittest	58.21% <100.00%> (-0.01%)	⬇️
unittestcli	56.58% <33.33%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[timvandermeij]

Thanks!