Fixed encoding matching for base64url in String.bytesFrom().

This closes #363 PR on GitHub.
diff --git a/src/njs_string.c b/src/njs_string.c
index 68e198d..f0159cd 100644
--- a/src/njs_string.c
+++ b/src/njs_string.c
@@ -1753,7 +1753,7 @@
     } else if (enc.length == 6 && memcmp(enc.start, "base64", 6) == 0) {
         return njs_string_decode_base64(vm, &vm->retval, &str);
 
-    } else if (enc.length == 9 && memcmp(enc.start, "base64url", 6) == 0) {
+    } else if (enc.length == 9 && memcmp(enc.start, "base64url", 9) == 0) {
         return njs_string_decode_base64url(vm, &vm->retval, &str);
     }
 
diff --git a/src/test/njs_unit_test.c b/src/test/njs_unit_test.c
index 4b8b505..5109d3a 100644
--- a/src/test/njs_unit_test.c
+++ b/src/test/njs_unit_test.c
@@ -9016,6 +9016,9 @@
     { njs_str("String.bytesFrom('QUJDRA#', 'base64url')"),
       njs_str("ABCD") },
 
+    { njs_str("String.bytesFrom('QUJDRA#', 'base64lol')"),
+      njs_str("TypeError: Unknown encoding: \"base64lol\"") },
+
     { njs_str("encodeURI.name"),
       njs_str("encodeURI")},