Ensure TextEdit's text is vertically aligned after resizing its height.

The current code only updates the alignment if the width of the
TextEdit changed, but we must also check if the height has changed.

Task-number: QTBUG-36069

[ChangeLog][QtDeclarative][TextEdit] Fixed TextEdit not vertically
aligning its text after having its height changed.

Change-Id: I428a01111874c70d2151213d2b3c5553e7f21186
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>