update dialog for high contrast mode

[Becky Gibson]

dialog is transparent in high contrast mode (in FF2 this is due to a FF bug but it should not be transparent in IE)

Currently the close arrow is not visible in high contrast mode so it needs a text alternative.

[bill]

Hmm, on FF in high-contrast mode the first time you show the dialog everything in the background disappears; the second time you show it, it's transparent.

[Becky Gibson]

(In [9286]) style changes and text alternative for close to allow dialog to work in high contrast mode. Refs #3493

[Becky Gibson]

The dialog will remain transparent in FF2 due to a FF2 bug that has been fixed for FF3.

The problem with the background not showing on the first instance of a dialog being displayed in high contrast mode has to do with the fadeIn and initial setup. If I comment out this._fadeIn.play() in dialog.show() - it works fine.

[Becky Gibson]

changed from 0.9beta to 0.9 since general high contrast mode support is fixed - just the one FF specific issue left

[Becky Gibson]

closed - remaining FF only issue is captured in #3548

[simonjb]

(In [12290]) Added a small comment to clarify a line of CSS (position:absolute) in the .dijitDialog .closeText rule; refs #3493.