Normalize TextInputWidget placeholder appearance x-browsers and make it compliant to WCAG level AAA.
Right now we're letting styling of placeholder text up to browser default.
Placeholder text is worrisome misused as replacement for labels like for example at VE's option panel. Let's make sure that placeholder text:
- looks the same across browsers
- fulfills level AAA compliance (contrast ratio 7:1) as it's the only input value indicator