Make some webp classes internal

src/ImageSharp/Formats/WebP/AlphaDecoder.cs

@@ -66,7 +66,7 @@ namespace SixLabors.ImageSharp.Formats.Webp
         }
 
         /// <summary>
-        /// Gets the the width of the image.
+        /// Gets the width of the image.
         /// </summary>
         public int Width { get; }
 
@@ -145,7 +145,7 @@ namespace SixLabors.ImageSharp.Formats.Webp
 
                 Span<byte> deltas = dataSpan;
                 Span<byte> dst = alphaSpan;
-                Span<byte> prev = null;
+                Span<byte> prev = default;
                 for (int y = 0; y < this.Height; ++y)
                 {
                     switch (this.AlphaFilterType)

src/ImageSharp/Formats/WebP/Lossless/HuffIndex.cs

@@ -6,7 +6,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
     /// <summary>
     /// Five Huffman codes are used at each meta code.
     /// </summary>
-    public static class HuffIndex
+    internal static class HuffIndex
     {
         /// <summary>
         /// Green + length prefix codes + color cache codes.

src/ImageSharp/Formats/WebP/Lossless/Vp8LTransformType.cs

@@ -8,7 +8,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
     /// that can reduce the remaining symbolic entropy by modeling spatial and color correlations.
     /// Transformations can make the final compression more dense.
     /// </summary>
-    public enum Vp8LTransformType : uint
+    internal enum Vp8LTransformType : uint
     {
         /// <summary>
         /// The predictor transform can be used to reduce entropy by exploiting the fact that neighboring pixels are often correlated.
@@ -16,7 +16,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
         PredictorTransform = 0,
 
         /// <summary>
-        /// The goal of the color transform is to decorrelate the R, G and B values of each pixel.
+        /// The goal of the color transform is to de-correlate the R, G and B values of each pixel.
         /// Color transform keeps the green (G) value as it is, transforms red (R) based on green and transforms blue (B) based on green and then based on red.
         /// </summary>
         CrossColorTransform = 1,

src/ImageSharp/Formats/WebP/WebpChunkType.cs

@@ -7,7 +7,7 @@ namespace SixLabors.ImageSharp.Formats.Webp
     /// Contains a list of different webp chunk types.
     /// </summary>
     /// <remarks>See WebP Container Specification for more details: https://developers.google.com/speed/webp/docs/riff_container </remarks>
-    public enum WebpChunkType : uint
+    internal enum WebpChunkType : uint
     {
         /// <summary>
         /// Header signaling the use of the VP8 format.