mishoo/UglifyJS2 — pull request #439 by Arnavion (2014-03-03 03:22:01+00:00)
Title: Handle the case when SourceMapConsumer.originalPositionFor returns null source.

This happens when SourceMapConsumer does not have a valid position to map the input line and column. This is a change in mozilla/source-map starting from version 0.1.33

Fixes #436