@return [Integer] The index to which the resolution should unwind in the
case of conflict.
@return [Object] the requirement that led to a version of a possibility
with the given name being activated.
Requires the dependencies that the recently activated spec has @param [Object] activated_spec the specification that has just been
activated
@return [void]
Pushes a new {DependencyState} that encapsulates both existing and new requirements @param [Array] new_requirements @return [void]