Example using v1.11.3: http://jsbin.com/dojupi/edit?html,js,output
Same example using v1.12.0: http://jsbin.com/nixide/edit?html,js,output
View the console in both and compare the results.
v1.11.3 says that #div-100-4's top is -100
whereas
v1.12.0 says that #div-100-4's top is 300.

Both Chrome and Firefox on OS X give the same results.

This appears to have broken the scaffolding of one of Bootstrap's unit tests (X-Ref: twbs/bootstrap#18904).

Perhaps related to #2828?