Fix typo (forgotten reference operator) in test.
Fix typo (forgotten reference operator) in test.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=171708408

dwing4g/leveldb,bitcoin-core/leveldb,google/leveldb,cmumford/leveldb,yuwolf/leveldb,olzhabay/PMIndexDB,matehat/leveldb,bitcoin-core/leveldb,matehat/leveldb,olzhabay/PMIndexDB,fastogt/leveldb,olzhabay/PMIndexDB,luke-jr/leveldb,bitcoin-core/leveldb,fastogt/leveldb,cmumford/leveldb,likema/leveldb,matehat/leveldb,yuwolf/leveldb,yuwolf/leveldb,fuchsia-mirror/third_party-leveldb,google/leveldb,luke-jr/leveldb,dwing4g/leveldb,fuchsia-mirror/third_party-leveldb,dwing4g/leveldb,likema/leveldb