fix missed IFrameMetaData method

src/ImageSharp/Formats/Gif/GifDecoderCore.cs

@@ -376,7 +376,7 @@ namespace SixLabors.ImageSharp.Formats.Gif
                 // This initializes the image to become fully transparent because the alpha channel is zero.
                 this.image = new Image<TPixel>(this.configuration, imageWidth, imageHeight, this.metaData);
 
-                this.SetFrameMetaData(this.metaData);
+                this.SetFrameMetaData(this.image.Frames.RootFrame.MetaData);
 
                 image = this.image.Frames.RootFrame;
             }
@@ -522,7 +522,7 @@ namespace SixLabors.ImageSharp.Formats.Gif
         /// </summary>
         /// <param name="metaData">The meta data.</param>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void SetFrameMetaData(IFrameMetaData metaData)
+        private void SetFrameMetaData(ImageFrameMetaData metaData)
         {
             if (this.graphicsControlExtension != null)
             {

tests/ImageSharp.Tests/MetaData/ImageMetaDataTests.cs

@@ -24,22 +24,18 @@ namespace SixLabors.ImageSharp.Tests
             ImageProperty imageProperty = new ImageProperty("name", "value");
 
             metaData.ExifProfile = exifProfile;
-            metaData.FrameDelay = 42;
             metaData.HorizontalResolution = 4;
             metaData.VerticalResolution = 2;
             metaData.Properties.Add(imageProperty);
             metaData.RepeatCount = 1;
-            metaData.DisposalMethod = DisposalMethod.RestoreToBackground;
 
             ImageMetaData clone = new ImageMetaData(metaData);
 
             Assert.Equal(exifProfile.ToByteArray(), clone.ExifProfile.ToByteArray());
-            Assert.Equal(42, clone.FrameDelay);
             Assert.Equal(4, clone.HorizontalResolution);
             Assert.Equal(2, clone.VerticalResolution);
             Assert.Equal(imageProperty, clone.Properties[0]);
             Assert.Equal(1, clone.RepeatCount);
-            Assert.Equal(DisposalMethod.RestoreToBackground, clone.DisposalMethod);
         }
 
         [Fact]