Michael Gratton authored Mar 06, 2019 and Michael Gratton committed Mar 07, 2019

This default instance was causing double the number of preferred height
events, which was likely creating a race for ConversationWebView. This
might (should?) fix plain text email with quotes sometimes showing up
with a vastly incorrect height.

To ensure that a PageState is constructed properly, make ClientWebView
abstract and use replace the one direct use of the class in the accounts
editor for the signature with a new subclass.

See #283