Unexpected dead code removal of string compare result #1592
Description
Run dead code removal on following code test.js
var result = ('a' === 'b');
var notTheSame = (result === false);
console.log(notTheSame); // notTheSame is truewith uglify@2.8.0, uglify@2.8.11
uglifyjs -c dead_code=true test.jswill output
WARN: Non-strict equality against boolean: == false [test.js:1,13]
var result=0,notTheSame=result===!1;console.log(notTheSame); // notTheSame is falseExpected output is
var result=!1,notTheSame=result===!1;console.log(notTheSame); // notTheSame is true