FTSE 250 up ahead of Brexit deal vote; miners hit by dismal China GDP

(Reuters) - London's mid-cap index was higher on Friday ahead of a parliamentary vote on the new Brexit deal, but miners slipped after data showed China's economic growth dropped to a near 30-year low.The FTSE 250 , up more than 4% since last week as a flurry of Brexit updates fuelled optimism, added another 0.4% by 0800 GMT. Cybersecurity firm Avast rose 6% after its results and helped the index outperform the European benchmark .The FTSE 100 edged 0.1% lower, as Brexit-sensitive stocks such..