test262/src/insignificant-input-elements
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This directory should contain a .case test case file for each character that is either WhiteSpace or LineTerminator. Because the former is defined in terms of the Unicode "Space_Separator" category, it can change over time even if the ECMAScript specification does not.

A current list can be fetched as [:Space_Separator:] using a tool such as the Unicode UnicodeSet utility: https://util.unicode.org/UnicodeJsps/list-unicodeset.jsp?a=%5B%3ASpace_Separator%3A%5D&g=&i=