Fix issue with Chrome 39.0.2171.95

In  Chrome 39.0.2171.95 (64-bit) the "this" inside the foreach is a Window object when the function is called from tool/mode_creator.js in the statement

require("ace/config").setDefaultValues("editor", {
    enableBasicAutocompletion: true,
    enableSnippets: true
});

This seems to have changed. It used to work in Chrome 39.0.2171.71. But since I updated 2 days ago whenever I run the mode_creator from a local ace served via static.py I get the error "undefined" is not a function at the this.setDefaultValue(...) call. When I placed a breakpoint there and inspected "this" it turned out to be a Window object.