Bug 1073415 - Add some polyfills for supporting IE for Loop's use of the l10n-gaia library and the TB SDK. r=dmose

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extra : rebase_source : 0f88c4405a43fc855d3485832b73c878d44c74a8
Bug 1091537 - Set navigator.originalGum after the TB sdk has loaded in case TBPlugin was defined. r=dmose a=kwierso