[css21] 4.2 Rules for handling parsing errors, question

Chapter http://www.w3.org/TR/CSS21/syndata.html#parsing-errors
is silent about CSS selectors parsing errors.

Let's say we have following:
b[href=], a[href="something"] { ... }

First selector is obviously erroneous.
Question: a) shall second one be considered as valid one and block following be 
used -or-
b) parser shall skip the whole fragment up to the end of the block?

I'd be happy if someone will explain how to handle such situations.

Andrew Fedoniouk.
http://terrainformatica.com