Fix issue where last 8 bits of D24X8 influence depth calculation.

src/common/mathutil.h

@@ -504,6 +504,7 @@ inline float normalizedToFloat(T input)
 {
     static_assert(std::numeric_limits<T>::is_integer, "T must be an integer.");
     static_assert(inputBitCount < (sizeof(T) * 8), "T must have more bits than inputBitCount.");
+    ASSERT((input & ~((1 << inputBitCount) - 1)) == 0);
 
     if (inputBitCount > 23)
     {

src/image_util/imageformats.cpp

@@ -1832,7 +1832,7 @@ void D16::WriteDepthStencil(D16 *dst, const DepthStencil *src)
 
 void D24X8::ReadDepthStencil(DepthStencil *dst, const D24X8 *src)
 {
-    dst->depth = gl::normalizedToFloat<24>(src->D);
+    dst->depth = gl::normalizedToFloat<24>(src->D & 0x00ffffff);
 }
 
 void D24X8::WriteDepthStencil(D24X8 *dst, const DepthStencil *src)

src/image_util/imageformats.h

@@ -751,7 +751,8 @@ struct D16
 
 struct D24X8
 {
-    uint32_t D;
+    uint32_t D : 24;
+    uint32_t X : 8;
 
     static void ReadDepthStencil(DepthStencil *dst, const D24X8 *src);
     static void WriteDepthStencil(D24X8 *dst, const DepthStencil *src);

src/tests/gl_tests/DepthStencilFormatsTest.cpp

@@ -416,9 +416,6 @@ TEST_P(DepthStencilFormatsTest, DepthStencilReadback_UShort)
 // This test will initialize a depth texture, clear it and read it back, if possible
 TEST_P(DepthStencilFormatsTest, DepthStencilReadback_UInt)
 {
-    // http://anglebug.com/4573
-    ANGLE_SKIP_TEST_IF(IsWindows() && IsVulkan());
-
     GLuint fakeData[10]    = {0};
     ReadbackTestParam type = {
         GL_DEPTH_ATTACHMENT, GL_DEPTH_COMPONENT, GL_UNSIGNED_INT, fakeData, 16, 0};