Bug 1101624 - use dummy page instead of about:blank to avoid a race, r=mconley

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extra : rebase_source : c4857c425e10096c30dfe01af7ea99f2a8c69c8e
Bug 1100419 - add --timeout switch to mochitets, r=ted

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extra : rebase_source : 21285fe8cbab61365f4c987b2119b7feb8d64c08