feat: HTTP add TLS fingerprint fallback (#1444)

pkg/download/engine/testdata/wpt/fetch/api/headers/headers-structure.any.js

@@ -0,0 +1,20 @@
+// META: title=Headers basic
+// META: global=window,worker
+
+"use strict";
+
+var headers = new Headers();
+var methods = ["append",
+                "delete",
+                "get",
+                "has",
+                "set",
+                //Headers is iterable
+                "entries",
+                "keys",
+                "values"
+                ];
+for (var idx in methods)
+  test(function() {
+    assert_true(methods[idx] in headers, "headers has " + methods[idx] + " method");
+  }, "Headers has " + methods[idx] + " method");