https://bugzilla.mozilla.org/show_bug.cgi?id=1504834#c5
https://bugzilla.mozilla.org/attachment.cgi?id=9028600
Rough progress patch


diff --git gfx/2d/DrawTargetSkia.cpp gfx/2d/DrawTargetSkia.cpp
index 050d9ae44e13..6f9bc7a88317 100644
--- gfx/2d/DrawTargetSkia.cpp
+++ gfx/2d/DrawTargetSkia.cpp
@@ -166,8 +166,7 @@ static IntRect CalculateSurfaceBounds(const IntSize& aSize, const Rect* aBounds,
   return surfaceBounds.Intersect(bounds);
 }
 
-static const int kARGBAlphaOffset =
-    SurfaceFormat::A8R8G8B8_UINT32 == SurfaceFormat::B8G8R8A8 ? 3 : 0;
+static const int kARGBAlphaOffset = 0;
 
 static bool VerifyRGBXFormat(uint8_t* aData, const IntSize& aSize,
                              const int32_t aStride, SurfaceFormat aFormat) {
diff --git gfx/skia/skia/modules/skcms/skcms.cc gfx/skia/skia/modules/skcms/skcms.cc
index 00b19eca7ed3..e6426c296df9 100644
--- gfx/skia/skia/modules/skcms/skcms.cc
+++ gfx/skia/skia/modules/skcms/skcms.cc
@@ -31,6 +31,8 @@
         #include <avx512fintrin.h>
         #include <avx512dqintrin.h>
     #endif
+#else
+    #define SKCMS_PORTABLE
 #endif
 
 using namespace skcms_private;
@@ -379,20 +381,28 @@ enum {
 static uint16_t read_big_u16(const uint8_t* ptr) {
     uint16_t be;
     memcpy(&be, ptr, sizeof(be));
-#if defined(_MSC_VER)
-    return _byteswap_ushort(be);
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+    return be;
 #else
+    #if defined(_MSC_VER)
+    return _byteswap_ushort(be);
+    #else
     return __builtin_bswap16(be);
+    #endif
 #endif
 }
 
 static uint32_t read_big_u32(const uint8_t* ptr) {
     uint32_t be;
     memcpy(&be, ptr, sizeof(be));
-#if defined(_MSC_VER)
-    return _byteswap_ulong(be);
+#if __BYTE_ORDER == __ORDER_BIG_ENDIAN__
+    return be;
 #else
+    #if defined(_MSC_VER)
+    return _byteswap_ulong(be);
+    #else
     return __builtin_bswap32(be);
+    #endif
 #endif
 }