* System_test.dll.sources: Added EventDescriptorCollectionTest.cs.
* EventDescriptorCollectionTests.cs: Added tests based on tests for
PropertyDescriptorCollection.
* PropertyDescriptorCollectionTests.cs: Added tests for Sort overloads.
Improved test for Find with null key.
* EventDescriptorCollection.cs: Fixed NRE in Sort overloads when order
string array is null.
* PropertyDescriptorCollection.cs: Fixed NRE in Sort overloads when
order string array is null.
svn path=/trunk/mcs/; revision=106733