Bug 1076836 - Stop storing a principal in txMozillaXSLTProcessor. r=bz.

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extra : rebase_source : 2132e67ad948a5068976b0a5ec513b623b08a4cd
Bug 1076836 - Stop storing a principal in txMozillaXSLTProcessor, pass the document to TX_LoadSheet. r=sicking.

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extra : rebase_source : 7254cc12fdf397e4929f80f835f4d48db751fb7d