Cameron was very keen on putting into law that he would not put up tax rates. A legally binding target which seems to have been forgotten about is to eliminate child poverty by 2020, or at least reduce it to below 10%. At the moment, it is 17% and will rise to 21% by 2020, according to the IFS, if there are £12 billion of social security cuts. It doesn't matter whether their parents are in work or out of work, children can still be poor.
The Guardian article also said that Labour had no shadow chancellor. Chris Leslie is the shadow chancellor, having worked in finance for over five years.
Oh yes, just read the Guardian article, and this is the relevant bit:
'The IFS said the scale of the overall savings - 10% of the part of the welfare bill not spent on pensioners - would involve the Conservatives looking at child benefit, child tax credit and disability allowances.'
So not what Osborne has said, just speculation by the IFS.