try to make themes look consistent when border-box is applied

[ben hockey]

​http://paulirish.com/2012/box-sizing-border-box-ftw/ encourages the use of border-box by applying the following style

* {
    -moz-box-sizing: border-box;
    box-sizing: border-box;
}

border-box is a more intuitive box model and so i can see that its likely developers will follow this advice.

if you look at themeTester with this setting, you'll see that the widgets are affected by this. we should look into seeing what we can do about it. we might even find that it could be possible to leverage border-box.

[bill]

See also #15104, I'm guessing that blocks this ticket but not sure.

[bill]

Amazingly it works pretty well (at least in trunk). I see layout problems for:

• TabContainer scrolling buttons
• space to the left and right of tabs; can be seen clearly by clicking on a dark color on the ColorPicker in the accordion
• slight problem with up/down arrow buttons on NumberSpinner

[bill]

Telling dojo/dom-geometry that your page is in box-model setting fixes all the problems except the tiny NumberSpinner layout glitch.

Would be nice if you didn't need to do that, which I noted in #15104.

Closing as duplicate of #15104.

[bill]

In [30685]:

code to test border-box sizing, refs #14931, #15104