[BUGFIX lts] Avoid console.trace for every Ember.warn

[rwjblue]

Originally (Ember < 3.2), Ember.warn used Ember.Logger as an abstraction layer in case console was not present. Since Ember.Logger was deprecated in emberjs/rfcs#297 the internals have been refactored to use console directly instead.

When that change was made, the following:

    Logger.warn(`WARNING: ${message}`);
    if ('trace' in Logger) {
      Logger.trace();
    }

Was changed to:

    console.warn(`WARNING: ${message}`);
    if (console.trace) {
      console.trace();
    }

This seems correct, however when you dig into it you will notice that the Ember.Logger class never had a .trace method! The reason for the original 'trace' in Logger check was specifically so that you could do Ember.Logger.trace = () => console.trace IIF you wanted to see where a given warning was coming from. That was added back in 2012, but since then the developer tools of modern browsers have gotten massively better. At this point, every console.log/console.warn tracks its stack trace so that you can drill into the source in the dev tools. The primary difference between that functionality and calling console.trace() directly like this is that with console.warn the stack trace is hidden by default (and has to be manually expanded), whereas with console.trace() it is always called and the full stack is printed.

tldr; when we refactored to address the Ember.Logger deprecation, we began calling console.trace for every Ember.warn invocation and the console.trace() calls make the console fairly unusable even with a very low volumn of warnings.