The answer lies in the couple sentences beforehand:
"The second edition of ECMA-262 was largely editorial. The standard was updated to get into strict agreement with ISO/IEC-16262 and didn't feature any additions, changes or omissions."
From the browser perspective, 1 & 2 are the same, so there are no new changes to implement.
The table on page 6 illustrates Netscape Navigator and Internet Explorer had already implemented Edition 1 before Edition 2, whereas Opera began their ECMAScript implementation when Edition 2 was already complete.