Backed out changeset 594c44cf5a05 (bug 939080) for breaking buildconfig

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extra : rebase_source : f526819fa1ad686d9d30f32311c8db037859d178
Add some comments about angle-build-unified.patch, no bug

DONTBUILD

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extra : rebase_source : 983dd29d0b8c254aeaa9dd8367accd34d0bd695d