This patch makes GetBounds(), GetScreenBounds() and GetClientBounds() more
obviously infallible, like existing functions such as GetNaturalBounds() and
GetClientSize(). This results in clearer behaviour in nsCocoaWindow.mm if
Objective C exceptions occur. Along the way, the patch removes some useless
failure checks for these functions.
The patch also removes the NS_IMETHOD from GetRestoredBounds and makes that
function MOZ_MUST_USE.
The patch renames the existing functions (GetBounds(), GetClientBounds(), etc)
by adding an |Untyped| suffix. It then adds typed equivalents, and uses those
typed equivalents in all the call sites where it's easy to do so. The trickier
remaining call sites are converted to use the Untyped-suffix version.
