Make GetLoadedAssembly() an extension method as well.

ILSpy.ReadyToRun/ReadyToRunLanguage.cs

@@ -70,7 +70,7 @@ namespace ICSharpCode.ILSpy
 		public override void DecompileMethod(IMethod method, ITextOutput output, DecompilationOptions options)
 		{
 			PEFile module = method.ParentModule.PEFile;
-			R2RReader reader = GetReader(null, module);
+			R2RReader reader = GetReader(module.GetLoadedAssembly(), module);
 			int bitness = -1;
 			if (reader.Machine == Machine.Amd64) {
 				bitness = 64;

ILSpy/LoadedAssemblyExtensions.cs

@@ -45,7 +45,7 @@ namespace ICSharpCode.ILSpy
 			return GetLoadedAssembly(file).GetTypeSystemOrNull();
 		}
 
-		static LoadedAssembly GetLoadedAssembly(PEFile file)
+		public static LoadedAssembly GetLoadedAssembly(this PEFile file)
 		{
 			if (file == null)
 				throw new ArgumentNullException(nameof(file));