Fix TypeError when retrieving innerText from elements containing <style>

[kent13n]

Description

This PR fixes a TypeError that occurs when retrieving innerText from an element that contains a <style> tag. The issue happens because the <style> tag introduces a CdataSection, which was not properly handled in the traversal process.
Related to the issue described in #460.

Fix:

The fix ensures that CdataSection nodes (introduced by <style> tags) are correctly handled during traversal.

• Updated Traversal::getNextNode()
  • Added a condition to check if the node is an instance of CdataSection.
  • If it is, we apply NodeFilter::FILTER_REJECT to exclude it from traversal.
• Updated Traversal::nextSkippingChildren()
  • Allowed CdataSection as a valid type for the $node parameter.

Impact:

Prevents crashes when processing innerText of elements containing <style> tags