Bug 940013 - fix Australis' CustomizableUI to have better interaction between registerToolbarNode and registerArea, r=Unfocused

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extra : rebase_source : 17670d2d198701a114b0fc7452f3ca72c1b835b2
Bug 940500 - Colorpicker tooltip now edits css gradients correctly. r=miker
Bug 944537 - No need to store showProgress as a Tab state/param (r=mfinkle)
Bug 944537 - Use message data to decide whether to show Tab progress or not (r=mfinkle)
Bug 944537 - No need to check for showProgress in BrowserToolbar (r=mfinkle)
Bug 944537 - Don't send showMessage boolean with Tabs.START event (r=mfinkle)
Bug 921942 - Broadcast scroll positions
Bug 921942 - Add FrameTree and scroll position broadcast tests