Fix textdiff.js whitespace indention

introduced in #373

Build error:
```
Running "less:production" (less) task
File public/css/styles.css created.

Running "jshint:web" (jshint) task
Linting components/textdiff/textdiff.js ...ERROR
[L57:C9] W015: Expected '}' to have an indentation at 11 instead at 9.
        });

Warning: Task "jshint:web" failed. Use --force to continue.

Aborted due to warnings.
```