For a file without translations, SvgFile::getInFileTranslations() currently returns text strings identified by the key fallback. However, SvgFile::getSavedLanguages() returns the languages of such a file with the key en (or whatever's given to SvgFile's constructor).

The latter should also be fallback.

Example with e.g. new SvgFile('InsertionIntoLinkedList1.svg', 'en'):

SvgFile::getInFileTranslations():

[
  "trsvg1" => [
    "fallback" => [...]
  ]
]

SvgFile::getSavedLanguages():

[
  0 => "en"
]