locl not working in Chrome/Firefox when showing individual punctuation

[NightFurySL2001]

When using OpenType locl feature to show individual CJK punctuations, in Chrome and Firefox some do not load the correct punctuation. See the left 2nd-6th column.

It is suspected that there is no script DFLT in feature file (only language dflt), while the punctuations are sc=Zyyy, so when Chrome calculate they become default (no preceding sc) and no script match them in feature.

Chrome: (Does not load any of them)

Firefox: (Does not load U+3001 、 and U+3002 。 for TW/HK)

It is fine in Microsoft Word and Adobe InDesign.

Word:

InDesign:

Test file: test.txt

[NightFurySL2001]

After testing, it is determined that missing the script DFLT in feature file is the main source of the bug above. Below shows a rebuilt Source Han Sans (JP) font which included a script DFLT with features copied from script latn, and does not exhibit the issue anymore.

Rebuilt font: SourceHanSans-Regular.zip
Feature file: features.OTC.J.txt
Important section:

......
feature locl {
  # DFLT SCRIPT
  script DFLT;

  language dflt;
  lookup latin_special;

  language JAN exclude_dflt;
  lookup jpcntwhk_special;

  language KOR exclude_dflt;
  lookup jp2kr;
  lookup kr_special;

  language ZHS exclude_dflt;
  lookup jp2cn;
  lookup jpcntwhk_special;

  language ZHT exclude_dflt;
  lookup jp2tw;
  lookup jpcntwhk_special;

  language ZHH exclude_dflt;
  lookup jp2hk;
  lookup jpcntwhk_special;

  # LATN SCRIPT
  script latn;
......

Chrome

Firefox