Wall Street Journal: In the midst of the global economic downturn, there’s one industry that’s expanding rapidly: China’s state-owned energy companies. Over the past few months, these companies have launched major multibillion-dollar oil deals from Russia to Brazil to Iraq. There’s a good lesson here for policy makers in Washington who think protectionism is costless. China is eager to secure a reliable and long-term supply of oil. The country is the second-largest oil consumer and importer in the world, …