"ObjectSupportLib is in the 9.0.4 Updater merely for the Installer application support, and not as a file which gets installed. With Apple's 'new new' installer engine introduced with OS 8.5 (as a more refined version of the 'new' installer introduced with OS 7.6), everything is integrated into one interface for the user's experience, but it is actually using several helper applications and support files in the background. These are all contained in the "Upgrader Files" folder. The contents are modular, and apparently the installer requires ObjectSupportLib in order to run."
above was taken from macsonly