Mixin for textarea widgets to add auto-expanding capability
See the dijit/form/_ExpandingTextAreaMixin reference documentation for more information.
Approximate the height when the textarea is invisible with the number of lines in the text. Fails when someone calls setValue with a long wrapping line, but the layout fixes itself when the user clicks inside so . . . In IE, the resize event is supposed to fire when the textarea becomes visible again and that will correct the size automatically.
Resizes the textarea vertically (should be called after a style/value change)