avm2: Remove final from ConvolutionFilter class declaration

Author: SuchAFuriousDeath

core/src/avm2/globals/flash/filters/ConvolutionFilter.as

@@ -1,5 +1,5 @@
 package flash.filters {
-    public final class ConvolutionFilter extends BitmapFilter {
+    public class ConvolutionFilter extends BitmapFilter {
         [Ruffle(NativeAccessible)]
         public var alpha:Number;