Baseclass for the <condition> task as well as several
conditions - ensures that the types of conditions inside the task
and the "container" conditions are in sync.
since: Ant 1.4
Create a dynamically discovered condition. Built-in conditions can
be discovered from the org.apache.tools.ant.taskdefs.condition
antlib.
Parameters: name - the condition to create. the dynamic condition if found, null otherwise.