ColorPalette: consider removing png files from non a11y mode

[Adam Peller]

If not in high contrast mode, perhaps we can do without the large png files and instead create the content programatically with a table or something. Also, perhaps it's possible to set title in a different way and avoid all those blank.gifs?

[bill]

We don't have or want separate codepaths for high contrast vs. normal (this is one of the axioms of dijit), so I don't see how this is possible, except by not having an image at all, and just displaying words in the table (for high contrast mode).

[bill]

(In [23979]) In non-high-contrast mode, use background-color CSS for color swatches, rather than an image. In high-contrast mode, make each color swatch contain an <img> node that loads the entire palette image, but scrolls/clips it to only show the color for that swatch.

This change avoids swatch/border alignment issues on webkit with a zoom setting, and alignment issues in other browsers, even when not zoomed, that started in 1.6, as seen in #12386.

Note that webkit never enters high contrast mode; even when the machine is set to high-contrast mode, the browser still displays background images. So webkit will always using background-color CSS.

Fixes #3919, #10959, #12386 in trunk/ and 1.6/ branch, !strict.

[bill]

(In [23990]) Remove unused files, the LTR files are now used even for RTL mode. Refs #3919.