Ruby 1.9.3 syntax for block as argument
===

So in Ruby 1.9.2-p290 I can do this

    content_for :something, do    
    end

which is quite nice.
But that's a syntax error in Ruby 1.9.3-p125 and instead I need to do this


    content_for(:something) do
    end


Where can I find documentation about this syntax restriction?
Is there any other way it could be written in 1.9.3-p125?