Editing tables using table properties dialog overwrites table's style values

[damo]

When a table is edited using the table properties dialog, its style attribute is overwritten with values from the dialog, including those style values that the table dialog does not manage, e.g. float, background-color etc.

E.g.

1. Create a default table
2. Edit the table in source mode and add background-color

<table border="1" cellpadding="1" cellspacing="1" style="background-color: red; width: 200px;">
	<tbody>

3. Go back to WYSIWYG mode and edit the table properties, leave default values and press OK.

Notice that the table's styles have been reset.

[garry.yao]

Fixed with [4572].