Bad search results in books

[FlafyDev]

The search results when searching queries in books are bad.

Here is how the search fails.

<p>This is a <span>short</span> paragraph</p>

Query	Found
This is a	true
short	true
paragraph	true
is a	true
short paragraph	false
This is a short	false
a short	false
This is a short paragraph	false

This weird results are because the search only searches inside text nodes. In this case there are 3 text nodes.