[GDomParser] Fix the mess on append child error.
[GDomParser] Fix the mess on append child error.

wavewave/lasem,gjtorikian/lasem,gjtorikian/lasem,wavewave/lasem,wavewave/lasem,gjtorikian/lasem,janmarthedal/mathml2svg,gjtorikian/lasem,janmarthedal/mathml2svg,janmarthedal/mathml2svg,wavewave/lasem,janmarthedal/mathml2svg