Further reducing object layout of SkipWhile.

Rx.NET/Source/src/System.Reactive/Linq/Observable/SkipWhile.cs

@@ -26,23 +26,22 @@ namespace System.Reactive.Linq.ObservableImpl
 
             private sealed class _ : Sink<TSource>, IObserver<TSource>
             {
-                private readonly Func<TSource, bool> _predicate;
-                private bool _running;
+                private Func<TSource, bool> _predicate;
 
                 public _(Func<TSource, bool> predicate, IObserver<TSource> observer, IDisposable cancel)
                     : base(observer, cancel)
                 {
                     _predicate = predicate;
-                    _running = false;
                 }
 
                 public void OnNext(TSource value)
                 {
-                    if (!_running)
+                    if (_predicate != null)
                     {
+                        var shouldStart = default(bool);
                         try
                         {
-                            _running = !_predicate(value);
+                            shouldStart = !_predicate(value);
                         }
                         catch (Exception exception)
                         {
@@ -50,9 +49,15 @@ namespace System.Reactive.Linq.ObservableImpl
                             base.Dispose();
                             return;
                         }
-                    }
 
-                    if (_running)
+                        if (shouldStart)
+                        {
+                            _predicate = null;
+
+                            base._observer.OnNext(value);
+                        }
+                    }
+                    else
                     {
                         base._observer.OnNext(value);
                     }
@@ -92,25 +97,24 @@ namespace System.Reactive.Linq.ObservableImpl
 
             private sealed class _ : Sink<TSource>, IObserver<TSource>
             {
-                private readonly Func<TSource, int, bool> _predicate;
-                private bool _running;
+                private Func<TSource, int, bool> _predicate;
                 private int _index;
 
                 public _(Func<TSource, int, bool> predicate, IObserver<TSource> observer, IDisposable cancel)
                     : base(observer, cancel)
                 {
                     _predicate = predicate;
-                    _running = false;
                     _index = 0;
                 }
 
                 public void OnNext(TSource value)
                 {
-                    if (!_running)
+                    if (_predicate != null)
                     {
+                        var shouldStart = default(bool);
                         try
                         {
-                            _running = !_predicate(value, checked(_index++));
+                            shouldStart = !_predicate(value, checked(_index++));
                         }
                         catch (Exception exception)
                         {
@@ -118,9 +122,15 @@ namespace System.Reactive.Linq.ObservableImpl
                             base.Dispose();
                             return;
                         }
-                    }
 
-                    if (_running)
+                        if (shouldStart)
+                        {
+                            _predicate = null;
+
+                            base._observer.OnNext(value);
+                        }
+                    }
+                    else
                     {
                         base._observer.OnNext(value);
                     }