Rust documentation doesn't show implementations when cookies / storage are disabled

```
TypeError: localStorage is null storage1.36.0.js:1:1164
    getCurrentValue file:///home/juergen/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/share/doc/rust/html/storage1.36.0.js:1
    <anonymous> file:///home/juergen/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/share/doc/rust/html/storage1.36.0.js:1
```