Remove support for the weird 5 byte pixel format.

Author: chinmaygarde

impeller/renderer/backend/metal/formats_mtl.h

@@ -25,8 +25,6 @@ constexpr PixelFormat FromMTLPixelFormat(MTLPixelFormat format) {
       return PixelFormat::kB8G8R8A8UNormInt;
     case MTLPixelFormatBGRA8Unorm_sRGB:
       return PixelFormat::kB8G8R8A8UNormIntSRGB;
-    case MTLPixelFormatDepth32Float_Stencil8:
-      return PixelFormat::kD32FloatS8UNormInt;
     case MTLPixelFormatRGBA8Unorm:
       return PixelFormat::kR8G8B8A8UNormInt;
     case MTLPixelFormatStencil8:
@@ -47,8 +45,6 @@ constexpr MTLPixelFormat ToMTLPixelFormat(PixelFormat format) {
       return MTLPixelFormatBGRA8Unorm;
     case PixelFormat::kB8G8R8A8UNormIntSRGB:
       return MTLPixelFormatBGRA8Unorm_sRGB;
-    case PixelFormat::kD32FloatS8UNormInt:
-      return MTLPixelFormatDepth32Float_Stencil8;
     case PixelFormat::kR8G8B8A8UNormInt:
       return MTLPixelFormatRGBA8Unorm;
     case PixelFormat::kS8UInt:

impeller/renderer/formats.h

@@ -52,9 +52,6 @@ enum class PixelFormat {
   kB8G8R8A8UNormIntSRGB,
   kS8UInt,
 
-  // Esoteric formats only used as render targets.
-  kD32FloatS8UNormInt,
-
   // Defaults. If you don't know which ones to use, these are usually a safe
   // bet.
   //
@@ -183,11 +180,6 @@ constexpr size_t BytesPerPixelForPixelFormat(PixelFormat format) {
     case PixelFormat::kB8G8R8A8UNormInt:
     case PixelFormat::kB8G8R8A8UNormIntSRGB:
       return 4u;
-    case PixelFormat::kD32FloatS8UNormInt:
-      // This is an esoteric format and implementations may use 64 bits.
-      // Impeller doesn't work with these natively and this return is only here
-      // for completeness. The 40 bits is as documented.
-      return 5u;
   }
   return 0u;
 }