Revert "fix(angular.equals): relax the comparison for undefined properties"

This reverts commit 3c2e1c5e4d12529b1d69a6173c38097527dccc4f.
Revert "Revert "fix(angular.equals): relax the comparison for undefined properties""

This reverts commit 0c4cba4b1178facc09d2e31b8ae60dcd35d39a00.