Anonymous text node in password field has `NS_MAYBE_MASKED` flag and
`TextEditor` managing the node has range of unmasking. This patch makes
`BuildTextRunsScanner::BuildTextRunForFrames()` treat text frame in
password field as `text-transform` applied. For recording the unmask range,
this patch creates `nsTransformedCharStyle::mMaskPassword` and treats unmask
range start/end edges as different style boundary. Therefore,
`nsCaseTransformTextRunFactory::TransformString()` can replace each character
with a password mask character with the information.
Note that we need to kill bidi algorithm in password fields with forms.css
because caret position will tell everybody whether the typing character is
an RTL or an LTR character.
Differential Revision: https://phabricator.services.mozilla.com/D38009
--HG--
extra : moz-landing-system : lando
Masayuki Nakano