Mangled names in debugger with source maps

Question

The debugger in Chrome/Safari does not show unmangled variable names when using source maps generated with grunt-contrib-uglify. Source code is displayed and debugged correctly. I have verified that the source map contains the variable names. Is this a bug in uglify?

Original source:

// two

function two()
{
    var test = "test";

    console.log("this is a " + test);
}

Generated source:

function two(){var a="test";console.log("this is a "+a)}
//# sourceMappingURL=all.min.js.map

Source map:

{
    "version": 3,
    "file": "all.min.js",
    "sources": ["../src/two.js"],
    "names": ["two","test","console","log"],
    "mappings":";;AAEA,QAASA,OAEL,GAAIC,GAAO,MAEXC,SAAQC,IAAI,aAAeF",
    "sourceRoot":"../"
}

Answer 1

As noted by @rd5, this is issue 327092 in Google Chrome, reported on 2013-12-09.

As of 2018-07-01, the issue is still unresolved.