render_text fix

[Maks Orlovich]

On Friday 07 July 2006 08:08, Pedro Suarez wrote:
> I was trying testkhtml from trunk, and it crashed with the pages I was
> testing.
> The errors were due to accesses to incorrect positions in the m_lines
> vector.

Good catch, please commit if you can... Sorry for missing this in the review 
of the original patch, I thought it would be fine due to reserve,but I guess 
it probably Q_ASSERTs?

-Maks