Cannot load URLs with special characters

```
What steps will reproduce the problem?
1. Use a SceneUrl URL like "http://example.com/foo%20bar.stl"

What is the expected output? What do you see instead?
- Even though the URL is properly-encoded, it fails to load the file.
- On the network, it shows that it actually tried to open
"http://example.com/foo%2520bar.stl"

What version of the product are you using? On what operating system?
- Latest SVN Checkout
- Google Chrome Canary 40

Please provide any additional information below.

This happens because it calls `encodeURI` on the URL even though it is already
properly encoded. To prevent double-encodings, `encodeURI` should not be called
here but by the implementor that uses the links if he thinks his URLs are not
properly encoded already.

The attached patch removes calls to `encodeURI` and fixes the problem.
```

Original issue reported on code.google.com by `negatif@gmail.com` on 13 Oct 2014 at 12:17

Attachments:
- [noEncodeUri.patch](https://storage.googleapis.com/google-code-attachments/jsc3d/issue-121/comment-0/noEncodeUri.patch)

Start by locating the encodeURI calls involved in loading SceneUrl links and reproduce the issue with a URL containing %20, such as http://example.com/foo%20bar.stl. Done means the already-encoded URL is requested unchanged rather than being double-encoded; the attached noEncodeUri.patch provides additional context.

Written by the indexing model from the issue text.