indent_dictionary_value after a comment breaks spaces around kw args

Here is one case where an inline comment between dictionary key and value introduces unrelated changes that are no longer PEP8-compliant.

**long-line.py**:
```python
return {
'link': # the link
'https://documents.example.com' + flask.url_for('document.index', document_id=1, document_title='foo'),
}
```

**yapf command to reproduce**
```
$ yapf --style '{based_on_style:pep8, indent_dictionary_value:True}' --diff long-line.py
--- long-line.py (original)
+++ long-line.py (reformatted)
@@ -1,4 +1,5 @@
return {
'link': # the link
- 'https://documents.example.com' + flask.url_for('document.index', document_id=1, document_title='foo'),
+ 'https://documents.example.com' + flask.url_for(
+ 'document.index', document_id = 1, document_title = 'foo'),
}
```

yapf correctly wraps the line to 80 chars and correctly indents the dictionary value... but it inserts unwanted spaces in the function's keyword args: `document_id = 1, document_title = 'foo'` where there were none before.

**Sub-par Workarounds**

* This is caused by the presence of the inline comment; deleting the comment produces somewhat different but at least PEP8-compliant code:
```
return {
'link':
- 'https://documents.example.com' + flask.url_for('document.index', document_id=1, document_title='foo'),
+ 'https://documents.example.com' +
+ flask.url_for('document.index', document_id=1, document_title='foo'),
}
```
* If we use the pep8 style's default value `indent_dictionary_value=True`, then yapf bails and does not re-format the line at all. I think this different issue is covered in #523. (My motivation for forcing `indent_dictionary_value=True` is to workaround #392)