R1:4566b86376bf

Fix two diff rendering bugs

Summary:
- The order of operations for file changes is wrong. We need to wrap them in a table, then render the changeset talbe around that table.
- Line data was being set to late, so renderShield() got the wrong line count and rendered empty diffs behind, e.g., generated changes.

Test Plan: Looked at an image change with property changes. Clicked "show file contents" on a generated file.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2009…