Handle JSON-style hash key as symbol

[aycabta]

RDoc handles the JSON-style hash key as identifier and operator :, like below:

<pre class="ruby">
{ <span class="ruby-identifier">hiee</span><span class="ruby-operator">:</span> <span class="ruby-value">:aaaa</span> }
{ <span class="ruby-identifier">class</span><span class="ruby-operator">:</span> <span class="ruby-value">:aaaa</span> }
</pre>

I think the hash key is a symbol. This Pull Request fixes it like below:

<pre class="ruby">
{ <span class="ruby-value">hiee:</span> <span class="ruby-value">:aaaa</span> }
{ <span class="ruby-value">class:</span> <span class="ruby-value">:aaaa</span> }
</pre>

[hsbt]

I understand this pull request and expected the behavior.

Original test of { class:"foo" } tokenize was strange expectation for me. Your fixed expectation is reasonable.