Tests that adding a new blank property works.

Text
Before append:
[expanded] 
element.style  { ()
font-size: 12px;

[expanded] 
div  { (user agent stylesheet)
display: block;


After insertion at index 0:
[expanded] 
element.style  { ()
margin-left: 3px;
font-size: 12px;

[expanded] 
div  { (user agent stylesheet)
display: block;


After appending and changing a 'compound' property:
[expanded] 
element.style  { ()
margin-left: 3px;
font-size: 12px;
color: red;
font-weight: bold;

[expanded] 
div  { (user agent stylesheet)
display: block;


After insertion at index 2:
[expanded] 
element.style  { ()
margin-left: 3px;
font-size: 12px;
/-- overloaded --/ third-property: third-value;
color: red;
font-weight: bold;

[expanded] 
div  { (user agent stylesheet)
display: block;