Bug 845631 - Remove nsXMLHttpProgressEvent, r=sicking

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extra : rebase_source : e5c6e80fbb656782bfe0f530c778cda9d9f97f0f
Bug 845863: Add a lookup for browser-scripts to allow loading a script only once. r=mbrubeck

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extra : rebase_source : 4eee7d026ead9cc1b3c5037efd20cda1e14c353f