mozilla/source-map — pull request #70 by glasser (2013-07-11 20:40:39+00:00)
Title: Fix SourceNode.fromStringWithSourceMap for empty maps.

Without this fix, if aSourceMapConsumer.eachMapping executes its callback zero
times, the lastMapping passed to the "remaining code" call to addMappingWithCode
will be null, causing a crash.