Bug 852040 - Apply use of BookmarkJSONUtils.importFromURL r=mbrubeck

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extra : rebase_source : 0b1a99da2455b86fce5aeae991d3f3384336e596
Bug 808770 - Implement pin/unpin of Top Sites, new Site model and refresh method on richgriditem. r=mbrubeck

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extra : rebase_source : 46fbc61a42d21ef41215f16fbeaf3501cfbb9ab7