fix code-testing involving @cff_analysis condition

[felipesanches]

While porting the new check com.adobe.fonts/check/cff_ascii_strings from OpenBakery (issue #4619), I left a test-case commented out because the cff_analysis condition is ignoring changes made to the ttFont object on a code-test.

The reason for that is that a new fonttools.ttLib.TTFont object is created based on the original file, which effectively discards any changes made by the code-test prior to invoking the check.

a326e75