Chrome Version: 60.3074

What steps will reproduce the problem?
(1) Open Chrome Tracing. 
(2) Start a trace.
(3) Stop a trace.

Observe: You see the string "Importing1 of 2"

Expect: Proper spacing.


//src/out/Debug/gen/content/browser/tracing/about_tracing.js contains:
function addStageForEachImporter(title,callback){lastTask=lastTask.after((task)=>{importers.forEach((importer,index)=>{var uiSubTask=task.subTask(()=>{progressMeter.update(`${title}${index+1}of ${importers.length}`);})   

But that space isn't missing in the original file.
https://cs.chromium.org/chromium/src/third_party/catapult/tracing/tracing/importer/import.html?type=cs&q=addStageForEachImporter&l=141

  var uiSubTask = task.subTask(() => {
      progressMeter.update(
          `${title} ${index + 1} of ${importers.length}`);
   });

It looks like the minifier might not be working properly with the new ES6 backtick strings feature?