Let me try to answer from the perspective of someone who also doesn't like his answers edited, if the edit doesn't add much value.
Obviously, the biggest issue is the "ownership" of the answer. There is an increasing number of people who are patrolling Stack Overflow in search of doing anything on a question or answer just so their picture/name can pop up as with "Edited" title (just take a look at popular questions/answers). When they do really edit the answer in a way that improves it (fix my terrible grammar, embed content from links I've posted, etc.) - great, no problem - everyone's happy.
But when they do something that does almost nothing to improve the answer or do something that can be filed under "subjective", I think whoever wrote that answer should have a right to revert the edit (at least until it transfers over to community ownership). Why? Well, it's his/hers answer - dammit - in most cases like this, for every keystroke of yours, the poster of the question/answer has at least 5-10.
In your specific case - we are talking about something that's highly subjective. From my perspective, you haven't improved readability; I would prefer code that doesn't contain tabs, i.e.:
javascript('foo = '+ function('text').value); // returns 0
javascript('bar'+ function('text').value == 1); // returns false
So, in cases like that my approach would be - if I really think my formatting is better - I would do an edit. If the owner of a question/answer reverts it, and I again think I'm right - I would flag. And if after all that, whoever wrote the question/answer sticks with his original post, I would let it be - I appreciate that he took the time to write that question/answer in the first place and out of that appreciation I would let him have his formatting.
EDIT: Now that I've found the answerfound the answer, I would say it's a question of bad code rather than formatting preference. The current format is as ugly as the original one. If I could, I would reformat it as:
var post = "http://www.example.com/";
'1a = '+ post.indexOf('http:') // 0
'1b '+ post.indexOf('http:') > -1 // false
'2a = '+ post.indexOf('www.') // 7
'2b '+ post.indexOf('www.') > -1 // false