Allow `CreateDelegate` to have return type covariance with methods that
return `enum` or `int` types.

This is from the upstream change at https://github.com/mono/mono/commit/122494330d635205b0a8766deaeafd0d79bd3d60.

[bcl] Allow conversion from enums and their basetypes in both directions with Delegate.CreateDelegate (). Fixes https://github.com/mono/mono/issues/6255. (case 977917)

* [bcl] Use RuntimeHelpers.GetHashCode () for getting the hash code of the delegate target to avoid calling user defined hash code implementations which can throw exceptions. Fixes a regression introduced by a48bc439.

* add test for #59235

https://bugzilla.xamarin.com/show_bug.cgi?id=59235

* [fixup] RuntimeHelpers.GetHashCode handles null

This was inadvertently removed in https://github.com/mono/mono/commit/611a43ee0f672adbac3e25dc77731843a3d10cf1 from MulticastDelegate.CombineImpl().

Add the type check back in the Delegate base class, we already do the same in Remove().

Add unit tests to cover the behavior to the corlib test suite. (reverted from commit f29878dc713f4e148fe0a1e703fae8929e6fb6e0)

Needed to update some monodoc tests to match that an exception is now thrown again.

.NET returns the method for the last delegate of the multicast delegate.

The comparison was failing because we were still using the method field (instead of the Method property), which would then return, in the case of a delegate to a virtual function, the method on the base class, instead of the method on the derived class. Updated the test cases to check that too.

Replace the reversed linked implementation by an array based implementation. This will improve Combine performance, as well as ease delegate to virtual function optimization.

The previous fix to handle curried delegates with DynamicInvoke did not correctly handle
those create with IL (in contrast to Delegate.CreateDelegate), as they don't hit any managed code.

The solution is to always require DelegateData to be filled for InvokeDynamic, if not, lazily
calculate it.

[corlib] Fix Delegate::DynamicInvoke for open delegates of instance methods and closed delegates of static methods

This should aid in tracking down bugs such as #11871 (or possibly even
fixing them) - if the problem still exists the process will run into
an infinite loop, which is a lot easier to debug (at least on iOS, and
likely other platforms too) than a stackoverflow.

	* Delegate.cs (CreateDelegate): Allow binding del(vt&) to an instance
	method of vt.

	* DelegateTest.cs: Add regression tests.

	Fixes #695978

	* Delegate.cs (CreateDelegate): Fix visibility and make
	sure that we fail to bind to first argument of static
	arguments to overloads that don't pass it.

	* DelegateTest.cs: Add tests for the previous change.

	Fixes #655439

2ec0ab59 caused a regression in
Create.Delegate where the overload which doesn't take a firstArgument
could be used to create closed over null delegates while this
overload doesn't allow it.

svn path=/trunk/mcs/; revision=154243

	* Delegate.cs (GetHashCode): Fix this so it is constant.

svn path=/trunk/mcs/; revision=146903

	* Jumbo patch to drop support for pre-NET_2_0 code:

	Remove ONLY_1_1 code
	Remove NET_1_0 only code
	Remove NET_2_0 defines assuming the value is true.

	Improve one MonoTODO;   Implement one MonoTODO/Niex.

	Ran a textual diff on the resulting assembly to validate that the
	restul is the same on NET_2_0


svn path=/trunk/mcs/; revision=144298

	* Delegate.cs (CreateDelegate): Support for delegates
	on static methods closed on a null target.


svn path=/trunk/mcs/; revision=130324

	* Delegate.cs: Add new parameter to CreateDelegate_internal (icall)
	* Environment.cs: Bump mono_corlib_version to 73


svn path=/trunk/mcs/; revision=130213

	* Delegate.cs (CreateDelegate): fix checks to deal with
	valuetypes -> obj conversions for arguments, and avoid
	issues with such unallowed conversion for return types.


svn path=/trunk/mcs/; revision=130175