Make Activator work only in observables.

Perspex/Styling/Activator.cs

@@ -21,27 +21,22 @@ namespace Perspex.Styling
 
         bool last = false;
 
-        public Activator(Match match)
+        public Activator(IEnumerable<IObservable<bool>> inputs)
         {
             int i = 0;
 
-            while (match != null)
+            foreach (IObservable<bool> input in inputs)
             {
                 int iCaptured = i;
 
-                if (match.Observable != null)
-                {
-                    this.values.Add(false);
-
-                    IDisposable subscription = match.Observable.Subscribe(
-                        x => this.Update(iCaptured, x),
-                        x => this.Finish(iCaptured),
-                        () => this.Finish(iCaptured));
-                    this.subscriptions.Add(subscription);
-                    ++i;
-                }
+                this.values.Add(false);
 
-                match = match.Previous;
+                IDisposable subscription = input.Subscribe(
+                    x => this.Update(iCaptured, x),
+                    x => this.Finish(iCaptured),
+                    () => this.Finish(iCaptured));
+                this.subscriptions.Add(subscription);
+                ++i;
             }
         }
 

Perspex/Styling/Match.cs

@@ -76,7 +76,20 @@ namespace Perspex.Styling
 
         public Activator GetActivator()
         {
-            return new Activator(this);
+            List<IObservable<bool>> inputs = new List<IObservable<bool>>();
+            Match match = this;
+            
+            while (match != null)
+            {
+                if (match.Observable != null)
+                {
+                    inputs.Add(match.Observable);
+                }
+
+                match = match.Previous;
+            }
+
+            return new Activator(inputs);
         }
 
         public override string ToString()