Bug 1041516 part 1: clean up pref code in shell service, r=bsmedberg

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extra : transplant_source : %B5%B9%11%7D%FE%86%85%7E%A5%10%11%5D%3B%1EZ%A4%B3%EF%0B%D8
Bug 1041516 part 2: reset the "check for default browser" pref to true when setting ourselves as the default browser, r=Gijs

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extra : transplant_source : %91r%EB%A5%9E%ED%15%3A9%EA%A98J%DBQH%DDt%8C%DF
Bug 1060675: only cap local form history results for the search bar if there are remote suggestions, r=MattN

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extra : transplant_source : n%E7%C9%B6%DC%01%21%966J%85%CFL%CC%DC%1E%DA6%AA%F5