fix: decoding uri in file_server (#3187)

std/http/file_server.ts

@@ -285,10 +285,10 @@ listenAndServe(
   addr,
   async (req): Promise<void> => {
     const normalizedUrl = posix.normalize(req.url);
-    const fsPath = posix.join(target, normalizedUrl);
+    const decodedUrl = decodeURIComponent(normalizedUrl);
+    const fsPath = posix.join(target, decodedUrl);
 
     let response: Response;
-
     try {
       const info = await stat(fsPath);
       if (info.isDirectory()) {

std/http/file_server_test.ts

@@ -79,3 +79,17 @@ test(async function serveFallback(): Promise<void> {
     killFileServer();
   }
 });
+
+test(async function serveFallback(): Promise<void> {
+  await startFileServer();
+  try {
+    const res = await fetch(
+      "http://localhost:4500/http/testdata/test%20file.txt"
+    );
+    assert(res.headers.has("access-control-allow-origin"));
+    assert(res.headers.has("access-control-allow-headers"));
+    assertEquals(res.status, 200);
+  } finally {
+    killFileServer();
+  }
+});