Fix #284 NotSupportedException thrown in NR CecilLoader

src/Libraries/NRefactory/ICSharpCode.NRefactory.Cecil/CecilLoader.cs

@@ -824,7 +824,13 @@ namespace ICSharpCode.NRefactory.TypeSystem
 		
 		void AddSecurityAttributes(SecurityDeclaration secDecl, IList<IUnresolvedAttribute> targetCollection)
 		{
-			var blobSecDecl = new UnresolvedSecurityDeclarationBlob((int)secDecl.Action, secDecl.GetBlob());
+			byte[] blob;
+			try {
+				blob = secDecl.GetBlob();
+			} catch (NotSupportedException) {
+				return; // https://github.com/icsharpcode/SharpDevelop/issues/284
+			}
+			var blobSecDecl = new UnresolvedSecurityDeclarationBlob((int)secDecl.Action, blob);
 			targetCollection.AddRange(blobSecDecl.UnresolvedAttributes);
 		}
 		#endregion