TextArea/SimpleTextArea: need focus indication

[bill]

TextBox indicates focus by changing the border color. Need something similar (or actually, the same) for TextArea/SimpleTextArea?.

Taken from ​IBM Design Leadership recommendations.

[bill]

(In [13362]) CSS fixes for TextArea? and TextBox? disabled and focused modes:

• make disabled TextBox? based widgets (like ComboBox?) have gray text, to disambiguate them from enabled states (fixes #6574).

• same for TextArea? and SimpleTextArea?. Exception is TextArea? on FF2, which is difficult because of the iframe (fixes #6087).

• make TextArea/SimpleTextArea? indicate focus with darker border, just like TextBox? based widgets (fixes #6470). Note that for TextArea? widget, _focused and _blurred where bad names for private methods, since they conflict w/the state variables used by FormWidget:setStateClass().

!strict