html.js: adjust _setMarginBox for TABLE and BUTTON which are border-box

[sjmiles]

Generally, non-DIV elements can have special margin, padding, or box handling in browsers which we cannot always detect via computedStyle.

In particular, TABLE and BUTTON elements use border-box even in strict (content-box) mode.

_setMarginBox is the only box function that depends on box model, add some simple checks to handle TABLE and BUTTON as border-box.

On FF 2.0, margins on TABLE appear to be completely undetectable (not available in style or computedStyle at all). To use a TABLE with box functions, it should be set to margin: 0.

[sjmiles]

(In [8943]) Fix _toStyleValue caching, refs #3295. Adjust _setMarginBox for TABLE and BUTTON, refs #3296. Adjust _setMarginBox left/top for non-Mozilla, refs #3297.

[sjmiles]

(In [9065]) Safari: add a null test and return a golem object from getComputedStyle if necessary. Refs #2686.

Adjust _setContentBox for TABLE and BUTTON, refs #3296.

Move left/top margin box adjustments out of _set and into _get. Refs #3297 and #3320.

Let _getContentBox fall back to offsetWidth/Height if clientWidth/Height are 0. Refs #3378.