2007-12-27 Miguel de Icaza <miguel@novell.com>

2007-12-27  Miguel de Icaza  <miguel@novell.com>

	* WebClient.cs: We catch exceptions that happen on the helper
	async threads toa void terminating the application on errors, and
	also raise a variant of the OnXXXXCompleted methods that take an
	Exception argument.

	Note that this differs from the .NET implementation in that
	we actually raise a signal on error, and set the exception, and in
	their case no error is ever raised.

	We now call CompleteAsync in the OnXXXCompleted handlers to ensure
	that the WebClient can be reused immediately by the callback.

	This fixes #350621.

	This also should fix the bug report on IRC where someone
	complained that they could not "chain" invocations to XXXAsync
	methods from the OnXXXXCompleted handlers due to the WebClient
	refusing to work if there was an ongoing operation

svn path=/trunk/mcs/; revision=91959