Fix error range for ETagRequired

[xorye]

When multiple child elements are missing their end tags, the error range refers to the parent element's start tag, rather than the child element's.

This error does not happen when only one child is missing their end tag.

Example XML file:

<?xml version="1.0" encoding="utf-8"?>
<picture>
    <p1></p1>
    <p2>    <!-- missing end tag -->
    <p3>    <!-- missing end tag -->
</picture>

Result:

Error message:
The element type "p3" must be terminated by the matching end-tag "</p3>".