twitter/bootstrap — pull request #8076 by maxsong1002 (2013-06-05 01:12:16+00:00)
Title: text-rendering: optimizelegibility causes problems in some languages

"text-rendering: optimizelegibility" style in type.less causes distortions in some languages with the current font.
Languages with 2-byte characters(Chinese, Korean, Japanese) seem to suffer from this.
I commented out optimizelegibility style that's applied in heading fonts to solve the problem.
After all, optimizelegibility does not seem necessary.