I have a change to the Web Inspector that smartly groups computed style properties under their short hand name. Except I rely on the engine's CSSComputedStyleDeclaration to give me a value if I pass it a shorthand name.
Similar to how CSSMutableStyleDeclaration will generate a shorthand value if you pass in a shorthand property name. However, shorthands should not be in the enumerable property list (just like CSSMutableStyleDeclaration).
See attached test case.
Created attachment 14472 [details]
Note, Firefox doesn't support this either. However, I don't think it would cause compatibility problems adding it to WebKit.
*** Bug 7703 has been marked as a duplicate of this bug. ***
It's safe to close it. I guess all common shorthand values are correctly return now.