Bug 879570 - Add mouse scroll support to start page r=mbrubeck

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extra : rebase_source : 7327481bec62faa7d106bab8685b30b317658fb6
Bug 775718 - Full scrollbars when using a mouse r=mbrubeck

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extra : rebase_source : 832f3c9109d2101439ace8cb80413dc5f0dd20e9