Fix the regex used to normalize css fonts in XFA

[calixteman]

The regex was quadratic in the number of consecutive spaces, which caused performance issues when normalizing fonts with a large number of spaces.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.00%. Comparing base (7fc7072) to head (491792f).

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #21680   +/-   ##
=======================================
  Coverage   90.00%   90.00%           
=======================================
  Files         263      263           
  Lines       66854    66855    +1     
=======================================
+ Hits        60173    60175    +2     
+ Misses       6681     6680    -1     

Flag	Coverage Δ
browsertest	66.54% <100.00%> (+<0.01%)	⬆️
fonttest	9.04% <0.00%> (-0.01%)	⬇️
integrationtest	69.36% <100.00%> (+<0.01%)	⬆️
unittest	57.83% <66.66%> (-0.02%)	⬇️
unittestcli	56.57% <66.66%> (+0.01%)	⬆️

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[timvandermeij]

r=me, with passing browser tests. Thank you for improving this!

[timvandermeij]

/botio browsertest

[moz-tools-bot]

From: Bot.io (Linux m4)

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Received

Command cmd_browsertest from @timvandermeij received. Current queue size: 0

Live output at: http://54.241.84.105:8877/8818e0c2a19f1e8/output.txt

[moz-tools-bot]

From: Bot.io (Windows)

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Received

Command cmd_browsertest from @timvandermeij received. Current queue size: 0

Live output at: http://54.193.163.58:8877/5b13901d9a08a7c/output.txt

[moz-tools-bot]

From: Bot.io (Linux m4)

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Success

Full output at http://54.241.84.105:8877/8818e0c2a19f1e8/output.txt

Total script time: 16.50 mins

• Regression tests: Passed

[moz-tools-bot]

From: Bot.io (Windows)

---

Success

Full output at http://54.193.163.58:8877/5b13901d9a08a7c/output.txt

Total script time: 23.42 mins

• Regression tests: Passed