some misc cleanups

BizHawk.Client.Common/movie/MovieService.cs

@@ -37,13 +37,7 @@ namespace BizHawk.Client.Common
 		/// <summary>
 		/// Gets the file extension for the default movie implementation used in the client
 		/// </summary>
-		public static string DefaultExtension
-		{
-			get
-			{
-				return "bk2";
-			}
-		}
+		public static string DefaultExtension => "bk2";
 
 		/// <summary>
 		/// Gets a list of extensions for all <seealso cref="IMovie"/> implementations

BizHawk.Client.Common/movie/tasproj/TasMovie.History.cs

@@ -8,7 +8,6 @@ namespace BizHawk.Client.Common
 	{
 		public TasMovieChangeLog(TasMovie movie)
 		{
-			_history = new List<List<IMovieAction>>();
 			_movie = movie;
 		}
 

BizHawk.Client.Common/movie/tasproj/TasMovieMarker.cs

@@ -51,7 +51,7 @@ namespace BizHawk.Client.Common
 
 			if (obj is TasMovieMarker)
 			{
-				return Frame == (obj as TasMovieMarker).Frame;
+				return Frame == ((TasMovieMarker)obj).Frame;
 			}
 			
 			return false;
@@ -59,13 +59,21 @@ namespace BizHawk.Client.Common
 
 		public static bool operator ==(TasMovieMarker marker, int frame)
 		{
-			// TODO: account for null marker
+			if (marker == null)
+			{
+				return false;
+			}
+
 			return marker.Frame == frame;
 		}
 
 		public static bool operator !=(TasMovieMarker marker, int frame)
 		{
-			// TODO: account for null marker
+			if (marker == null)
+			{
+				return false;
+			}
+
 			return marker.Frame != frame;
 		}
 	}

BizHawk.Client.Common/movie/tasproj/TasMovieRecord.cs

@@ -5,7 +5,6 @@
 		public bool? Lagged { get; set; }
 		public bool? WasLagged { get; set; }
 		public string LogEntry { get; set; }
-
 		public bool HasState { get; set; }
 	}
 }