[css-typed-om] StylePropertMap.set for non-list properties

[darrnshn]

What should StylePropertyMap.set do for non-list properties when given multiple arguments? e.g.

styleMap.set('width', CSS.px(1), CSS.px(2), CSS.px(3));
styleMap.getAll('width'); // ???

According to the spec, the "property model" will contain an entry ("width", [1px, 2px, 3px]). It's then unclear what getAll should return. If we follow the spec strictly, we return [[1px, 2px, 3px]] (a single-element list containing a 3-element list), which is probably not right... Should set throw an exception or just set the first element?

[tabatkins]

Actually, it just silently treats all properties as list-valued, even when they're not. This is still a bug tho - it's inconsistent with how .append() works on single-valued properties (it throws). We should be consistent here and just throw in both situations, so calling .set() on a single-valued property with more than one value should throw a TypeError.