Fix for issue #1455 - Inherited Class generated code does not match order of execution

[alanning]

Fix for Issue #1455. When I first looked at the generated code from the Class example on the website, I couldn't figure out how it wasn't throwing an error. Explained why it works and how it can be confusing in the issue description.

Question: If the patch is accepted, will the class example be automatically updated once the project is rebuilt?

(It's my first time committing so I apologize if I did something incorrectly. I made changes in a local branch 'fix_1455', then merged with my master, then submitted a pull request as described in the git tutorial found here)

[jashkenas]

I think that we actually want to leave the ordering as is ... just in case you do something tricky and immediately look for an inherited static property, within the constructor expression.

It looks backwards, but semantically, I think it makes sense to have the prototype chain be the very first thing that happens to a class, before the constructor body is even defined.