Problem/Motivation
#1849564: Add the symfony validator component to core despite Symfony potentially releasing BC-breaking updates after 2.3. added the interface from Symfony's translation component. This is only required because validator references that interface (and hence has a dependency), we never actually use the translation component anywhere in core. In that patch a .gitignore trick was used to avoid pulling in the entire library.
There was supposed to be a follow-up to sort this out properly - see #1849564-52: Add the symfony validator component to core despite Symfony potentially releasing BC-breaking updates after 2.3., but as far as I know that never got filed.
In the meantime, subsequent composer updates have brought in the full component. This is potentially confusing to people because they might think we actually use it (incuding posting to planet about that fact today hence me opening this issue), whereas Drupal's translation system is completely separate and none of the code gets executed ever.
Proposed resolution
Either remove everything except the interface again, or find a way to document really clearly why it's there.
