ResolveSatelliteAssembly should ...

ResolveSatelliteAssembly should always be called on the ALC which loaded parentAssembly

Simplify code.
Add Debug.Assert

Author: sdmaclea

src/System.Private.CoreLib/shared/System/Runtime/Loader/AssemblyLoadContext.Unix.cs

@@ -114,17 +114,15 @@ public bool Equals(ref ReadOnlySpan<char> entryName)
             if (parentAssembly == null)
                 return null;
 
-            AssemblyLoadContext? parentAlc = GetLoadContext(parentAssembly);
-
-            if (parentAlc == null)
-                return null;
+            // ResolveSatelliteAssembly should always be called on the ALC which loaded parentAssembly
+            Debug.Assert(this == GetLoadContext(parentAssembly));
 
             string parentDirectory = Path.GetDirectoryName(parentAssembly.Location)!;
 
             string assemblyPath = $"{parentDirectory}/{cultureName}/{assemblyName.Name}.dll";
             if (Internal.IO.File.InternalExists(assemblyPath))
             {
-                return parentAlc.LoadFromAssemblyPath(assemblyPath);
+                return LoadFromAssemblyPath(assemblyPath);
             }
             else if (Path.IsCaseSensitive)
             {
@@ -134,7 +132,7 @@ public bool Equals(ref ReadOnlySpan<char> entryName)
                 {
                     assemblyPath = $"{parentDirectory}/{caseInsensitiveCultureName}/{assemblyName.Name}.dll";
                     if (Internal.IO.File.InternalExists(assemblyPath))
-                        return parentAlc.LoadFromAssemblyPath(assemblyPath);
+                        return LoadFromAssemblyPath(assemblyPath);
                 }
             }
             return null;

src/System.Private.CoreLib/shared/System/Runtime/Loader/AssemblyLoadContext.Windows.cs

@@ -27,17 +27,15 @@ public partial class AssemblyLoadContext
             if (parentAssembly == null)
                 return null;
 
-            AssemblyLoadContext? parentAlc = GetLoadContext(parentAssembly);
-
-            if (parentAlc == null)
-                return null;
+            // ResolveSatelliteAssembly should always be called on the ALC which loaded parentAssembly
+            Debug.Assert(this == GetLoadContext(parentAssembly));
 
             string parentDirectory = Path.GetDirectoryName(parentAssembly.Location)!;
 
-            string assemblyPath = Path.Combine(parentDirectory, dir, $"{assemblyName.Name}.dll");
+            string assemblyPath = Path.Combine(parentDirectory, cultureName, $"{assemblyName.Name}.dll");
             if (Internal.IO.File.InternalExists(assemblyPath))
             {
-                return parentAlc.LoadFromAssemblyPath(assemblyPath);
+                return LoadFromAssemblyPath(assemblyPath);
             }
 
             return null;