move digest cache on to the DetailsKey object

This moves digest calculation cache on to the details key object.
Before, the digest cache was a class level ivar, and one of the keys was
the hash value of the details key object:

  https://github.com/rails/rails/blob/13c4cc3b5aea02716b7459c0da641438077f5236/actionview/lib/action_view/digestor.rb#L28

An object's hash value is not unique, so it's possible for this cache
key to produce colliding keys with no resolution.  This commit move
cache on to the details key object itself, so we know that the digests
are always unique per details key object.

0 files changed, 0 insertions, 0 deletions