fixed debug string formatting for structure
fixed debug string formatting for structure

Summary:
Fixed minor issue:
* use double spaces instead of a tab character for indentation
* depth should increase by 1, not 2

Reviewed By: shergin

Differential Revision: D7332803

fbshipit-source-id: 74fda2c7a4be4f509270d3074a7d71a3d4d32fe4

hammerandchisel/react-native,janicduplessis/react-native,pandiaraj44/react-native,javache/react-native,arthuralee/react-native,janicduplessis/react-native,hoangpham95/react-native,janicduplessis/react-native,exponentjs/react-native,facebook/react-native,facebook/react-native,pandiaraj44/react-native,hammerandchisel/react-native,javache/react-native,myntra/react-native,hammerandchisel/react-native,exponent/react-native,arthuralee/react-native,myntra/react-native,hoangpham95/react-native,exponentjs/react-native,facebook/react-native,exponent/react-native,exponentjs/react-native,hoangpham95/react-native,javache/react-native,exponentjs/react-native,janicduplessis/react-native,javache/react-native,exponentjs/react-native,myntra/react-native,exponentjs/react-native,pandiaraj44/react-native,exponent/react-native,facebook/react-native,javache/react-native,javache/react-native,myntra/react-native,hammerandchisel/react-native,myntra/react-native,hammerandchisel/react-native,exponent/react-native,hoangpham95/react-native,exponent/react-native,hammerandchisel/react-native,janicduplessis/react-native,janicduplessis/react-native,hammerandchisel/react-native,myntra/react-native,hoangpham95/react-native,arthuralee/react-native,myntra/react-native,janicduplessis/react-native,pandiaraj44/react-native,pandiaraj44/react-native,javache/react-native,exponent/react-native,exponent/react-native,facebook/react-native,hoangpham95/react-native,myntra/react-native,pandiaraj44/react-native,myntra/react-native,facebook/react-native,pandiaraj44/react-native,hoangpham95/react-native,pandiaraj44/react-native,arthuralee/react-native,exponent/react-native,hammerandchisel/react-native,javache/react-native,javache/react-native,exponentjs/react-native,facebook/react-native,exponentjs/react-native,facebook/react-native,facebook/react-native,arthuralee/react-native,janicduplessis/react-native,hoangpham95/react-native