[pug-code-gen] Extra line break pretty if block in mixin contain only text

[jeromew]

From @werty1001 on October 21, 2016 19:36

Hi, extra line break pretty if block in mixin contain only text or inline tags:

mixin test()
    .test&attributes(attributes): block

// Call
+test Test text

Output:

<div class="test">Test text
</div>

Instead of:

<div class="test">Test text</div>

I explored pug-code-gen/index.js but dont't found how to fix it.

Copied from original issue: pugjs/pug-code-gen#29