In System.Collections.Generic:

In System.Collections.Generic:
	* Dictionary.cs (GetKeys, GetValues): Remove.
	(SetThreshold): New function to calculate the resize threshold.
	(CopyTo): Don't use foreach syntax.
	(ContainsValue): Likewise.  Use default equality comparer of the
	value type.
	(GetObjectData): Use CopyTo to copy into temporary array.  Don't
	save redundant _usedSlots and _threshold.
	(OnDeserialization): Rewrite.
	(ICollection<>.CopyTo): Forward to CopyTo.
	(Enumerator._nextIndex): Rename to from _index.
	(Enumerator._next, Enumerator.FixNext): Remove.
	(Enumerator.Current): Rewrite to avoid need for _next.
	(Enumerator.IEnumerator.Reset): Update.
	(KeyCollection): Is also IEnumerable<TKey> and IEnumerable.
	Update methods to conform to standard.
	(KeyCollection.GetEnumerator): Restore.  Return the correct type.
	(KeyCollection.Enumerator): Rename from KeyEnumerator.  Simple
	wrapper that forwards to Dictionary<,>.Enumerator.
	(ValueCollection): Likewise.

In Test/System.Collections.Generic:
	* DictionaryTest.cs (SliceCollectionsEnumeratorTest): New test
	based on #75053.

svn path=/trunk/mcs/; revision=46087