Fix slow optimization of nested binary expressions (#248)

+semver:fix

Author: nur-sgaertner

src/DelegateDecompiler.Tests/Issue220And243.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Diagnostics;
+using System.Linq.Expressions;
+using NUnit.Framework;
+
+namespace DelegateDecompiler.Tests
+{
+    [TestFixture]
+    public class Issue220And243
+    {
+        [Test]
+        public void ShouldOptimizeSimpleExpressionQuickly()
+        {
+            // Somewhat artificial example, as Contains could be used instead. But the problem exists for every combination of binary operators.
+            Expression<Func<Employee, bool>> expr = e => e.Id == 1 || e.Id == 2 || e.Id == 3 || e.Id == 4 || e.Id == 5 || e.Id == 6 || e.Id == 7 || e.Id == 8
+                || e.Id == 9 || e.Id == 10 || e.Id == 11 || e.Id == 12 || e.Id == 13 || e.Id == 14 || e.Id == 15 || e.Id == 16 || e.Id == 17 || e.Id == 18
+                || e.Id == 19 || e.Id == 20 || e.Id == 21 || e.Id == 22 || e.Id == 23 || e.Id == 24 || e.Id == 25 || e.Id == 26 || e.Id == 27;
+
+            var sw = Stopwatch.StartNew();
+            OptimizeExpressionVisitor.Optimize(expr);
+
+            // Not so good to test runtime performance, but it's a working indicator. On my machine without fix > 20 s, with fix < 10 ms.
+            Assert.That(sw.ElapsedMilliseconds, Is.LessThan(1000));
+        }
+    }
+}

src/DelegateDecompiler/OptimizeExpressionVisitor.cs

@@ -330,7 +330,7 @@ left is MethodCallExpression expression &&
                 }
             }
 
-            return base.VisitBinary(node);
+            return node.Update(left, VisitAndConvert(node.Conversion, nameof (VisitBinary)), right);
         }
 
         protected override Expression VisitUnary(UnaryExpression node)