Pass post ID to post revision field filter

[pollett]

When viewing a post revision, for each field the filter

_wp_post_revision_field_xx

is called. This is passed the field name and value as parameters but not the post ID that it's working with, this allows you to modify the value based on it's currently contents but not based on the post ID i.e. to inject new fields into the diff.

Proposal that the post ID also be passed to this filter rather than having to hack around it by making $left and $right global.

[pollett]

Add post ID to revision field filter

[scribu]

Why not pass the whole revision instead of just the ID, then?

[pollett]

Pass complete revision to revision field filter

[pollett]

Passing the whole revision seems fairly reasonable. Patch added.

[westi]

Adding as a candidate for the Revisions work in 3.6

[ethitter]

In ​19932.1.patch, I refreshed the patch and added the entire revision to the third instance of the filter. I also added the revision side to the uses, or an empty string when not in a diff.

[adamsilverstein]

looks good.

[westi]

In 23404:

Revisions: Pass the whole revision being filtered along with context about which side it is to the _wp_post_revision_field_$field filters.

Fixes #19932 props pollett, ethitter.