Remove webkit properties from content moderation

All the modern browsers support display: flex and other related properties. We don't need -webkit-flex anymore.

Ref: https://caniuse.com/flexbox

.entity-moderation-form {
  display: -webkit-flex; /* Safari */
  display: flex;
  -webkit-flex-wrap: wrap; /* Safari */
  flex-wrap: wrap;
  -webkit-align-items: flex-start; /* Safari */
  align-items: flex-start;
  list-style: none;
}

.entity-moderation-form__item:last-child {
  -webkit-align-self: flex-end; /* Safari */
  align-self: flex-end;
  margin-right: 0;
}

Proposed resolution:

Remove these properties:

.entity-moderation-form {
  - display: -webkit-flex; /* Safari */
  display: flex;
  - -webkit-flex-wrap: wrap; /* Safari */
  flex-wrap: wrap;
  - -webkit-align-items: flex-start; /* Safari */
  align-items: flex-start;
  list-style: none;
}

.entity-moderation-form__item:last-child {
  -webkit-align-self: flex-end; /* Safari */
  align-self: flex-end;
  margin-right: 0;
}