startIndex not updated after a self-closing XML tag

[thewilkybarkid]

After debugging parcel-bundler/parcel#6752 (comment), the following XML:

<xml><a/><b/></xml>

gives the same startIndex on theb openTag event as it did for the a openTag (5, rather than the expected 9).

[fb55]

Thanks for the report! Fixed this in #949 and released as 7.1.2.