<Swing Dev> [14] RFR 8226513:, JEditorPane is shown with incorrect size

[semyon.sadetsky at oracle.com]

bug: https://bugs.openjdk.java.net/browse/JDK-8226513

webrev: http://cr.openjdk.java.net/~ssadetsky/8226513/webrev.00/

The fix adds resetting the root view initialization flag when the text 
component underling document is changed and also removes the check for 
the zero component size for the root view initialization to correct the 
resulting preferred component size in some scenarios when the root view 
need to be initially layouted.

--Semyon