iOS 8.2 Siri text is deleted after entered on Safari web forms.
After upgrading to iOS 8.2, Siri erases all text that's entered on Safari web forms.
iPad Air Wi-Fi, Cellular, iOS 8.2, null
That's a bug in iOS 8.2.
To work-around the dictation loss in Safari rather than touch the Done button to end the dictation just touch the text field.
if the dictation is lost because Siri times out just shake the iPad to bring up the Undo facility or press the .?123 key at the lower-left of the keyboard and touch the undo key
Report your Siri dictation bugs to Apple at http://www.apple.com/feedback/ipad.html