Ignore private annotation for constructors

[lambertjamesd]

I ended up adding an isConstructor check in many places where there is an isPrivate check. I also made it so it doesn't emit the constructor if it is private. It doesn't prevent calling new on a private class but I felt that was the logic thing to do until typescript supports private constructors.

[googlebot]

We found a Contributor License Agreement for you (the sender of this pull request), but were unable to find agreements for the commit author(s). If you authored these, maybe you used a different email address in the git commits than was used to sign the CLA (login here to double check)? If these were authored by someone else, then they will need to sign a CLA as well, and confirm that they're okay with these being contributed to Google.

[googlebot]

We found a Contributor License Agreement for you (the sender of this pull request), but were unable to find agreements for the commit author(s). If you authored these, maybe you used a different email address in the git commits than was used to sign the CLA (login here to double check)? If these were authored by someone else, then they will need to sign a CLA as well, and confirm that they're okay with these being contributed to Google.

[googlebot]

CLAs look good, thanks!

[googlebot]

CLAs look good, thanks!

[rkirov]

merged