Added cenecllationtoken work around.

Mono crashes on default cancellation token.

ICSharpCode.NRefactory/CSharp/Analysis/ControlFlow.cs

@@ -143,7 +143,12 @@ namespace ICSharpCode.NRefactory.CSharp.Analysis
 		Dictionary<string, ControlFlowNode> labels;
 		List<ControlFlowNode> gotoStatements;
 		
-		public IList<ControlFlowNode> BuildControlFlowGraph(Statement statement, ITypeResolveContext context, CancellationToken cancellationToken = default(CancellationToken))
+		public IList<ControlFlowNode> BuildControlFlowGraph(Statement statement, ITypeResolveContext context)
+		{
+			return BuildControlFlowGraph(statement, context, CancellationToken.None);
+		}
+		
+		public IList<ControlFlowNode> BuildControlFlowGraph(Statement statement, ITypeResolveContext context, CancellationToken cancellationToken)
 		{
 			return BuildControlFlowGraph(statement, new ResolveVisitor(
 				new CSharpResolver(context, cancellationToken),

ICSharpCode.NRefactory/CSharp/Analysis/DefiniteAssignmentAnalysis.cs

@@ -79,12 +79,22 @@ namespace ICSharpCode.NRefactory.CSharp.Analysis
 		
 		Queue<DefiniteAssignmentNode> nodesWithModifiedInput = new Queue<DefiniteAssignmentNode>();
 		
-		public DefiniteAssignmentAnalysis(Statement rootStatement, CancellationToken cancellationToken = default(CancellationToken))
+		public DefiniteAssignmentAnalysis(Statement rootStatement)
+			: this(rootStatement, null, CancellationToken.None)
+		{
+		}
+		
+		public DefiniteAssignmentAnalysis(Statement rootStatement, CancellationToken cancellationToken)
 			: this(rootStatement, null, cancellationToken)
 		{
 		}
 		
-		public DefiniteAssignmentAnalysis(Statement rootStatement, ITypeResolveContext context, CancellationToken cancellationToken = default(CancellationToken))
+		public DefiniteAssignmentAnalysis(Statement rootStatement, ITypeResolveContext context)
+			: this(rootStatement, context, CancellationToken.None)
+		{
+		}
+		
+		public DefiniteAssignmentAnalysis(Statement rootStatement, ITypeResolveContext context, CancellationToken cancellationToken)
 			: this(rootStatement, new ResolveVisitor(new CSharpResolver(context ?? MinimalResolveContext.Instance, cancellationToken),
 			                                         null, ConstantModeResolveVisitorNavigator.Skip))
 		{

ICSharpCode.NRefactory/CSharp/Resolver/CSharpResolver.cs

@@ -26,11 +26,8 @@ namespace ICSharpCode.NRefactory.CSharp.Resolver
 		internal readonly CancellationToken cancellationToken;
 		
 		#region Constructor
-		public CSharpResolver(ITypeResolveContext context)
+		public CSharpResolver(ITypeResolveContext context) : this (context, CancellationToken.None)
 		{
-			if (context == null)
-				throw new ArgumentNullException("context");
-			this.context = context;
 		}
 		
 		public CSharpResolver(ITypeResolveContext context, CancellationToken cancellationToken)