threerings/Starling-Framework — comment on commit c347a93fe8a37341d813c52a8db1b0885a2adc23
File:  line 0
By groves:

When DisplayObjectContainers without children calculate their bounds, they get a Matrix relative to the target space that includes their translation. Then the translation is included again in the calculation of the position by the matrix. This change removes the translation from the call to the matrix.