Improve performance of 'parseWithNormalisedSpaces' that is unconditio…

[qwwdfsad]

…nally invoked for each HTML text element

Addresses #2729

[IgnatBeresnev]

I remember we wanted to do some benchmarking of this change, but then we kinda forgot about it and now I'm not sure when I'll have time for it

@qwwdfsad would you be OK if we merge it as is, without additional benchmarking? The code/solution is clear to me, there's a comment, plus there's a very good description in #2729

[qwwdfsad]

I'm totally good.

It cuts a significant portion of allocations and CPU, but alas the actual execution time is dominated by classloader per task stuff. So the only downside of merging it now is that we won't be able to brag with "we improved performance by 30%" (as if we did it after Worker isolation)