Edison International, PG&E Corp. and other suppliers of electricity in California will be required by state regulators to cut greenhouse-gas emissions. Power companies in the most populous state will face a cap intended to bring emissions down, possibly to 1990 levels, according to a measure approved Thursday by the California Public Utilities Commission. Gov. Arnold Schwarzenegger said last year that he wanted the state to cut greenhouse-gas emissions to 1990 levels by 2020. The state would be the first to regulate emissions by electricity providers. "It's a very positive first step in the right direction," said Dan Kalb, the California...