Revert 226446 "Change _ITERATOR_DEBUG_LEVEL to 1 on Release builds"

> Change _ITERATOR_DEBUG_LEVEL to 1 on Release builds
> 
> VS2010 changed the default to 0 meaning weaker checks in our
> release builds.  This commit changes it back again.
> 
> BUG=289691
> NOTRY=true
> 
> Review URL: https://codereview.chromium.org/23464081

TBR=wfh@chromium.org

Review URL: https://codereview.chromium.org/25445003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226462 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226462