title: RegeneratorRuntime is not defined
body: <p>I am trying to run <a href="https://www.npmjs.com/package/karma-babel-preprocessor">Karma-babel-preprocessor</a> and a straight forward ES6 generator:</p>
  
  <pre><code>//require('babel/polyfill');
  
    describe("how Generators work", function() {
      it("will allow generator functions", function() {
        /*function * numbers() {
          yield 1;
          yield 2;
          yield 3;
        };*/
  
  
        let numbers = {
          [Symbol.iterator]:function*(){
              yield 1;
              yield 2;
              yield 3;
            }
        }
  
        let sum = 0;
  
        for(n of numbers){
          sum += n;
        }
  
        expect(sum).toBe(6);
      });
    });
  </code></pre>
  
  <p>From this I generated my test files (ES6 => ES5) with babel:</p>
  
  <p><code>babel src --watch --out-dir tests</code> </p>
  
  <p>Then I run <code>karma start</code> I get error: </p>
  
  <blockquote>
    <p>ReferenceError: regeneratorRuntime is not defined".  </p>
  </blockquote>
  
  <p>Relevant bits in karma.conf.js:</p>
  
  <pre><code>  // list of files / patterns to load in the browser
      files: [
        'test-main.js',
        {pattern: 'tests/*.js', included: true}
      ],
  
  
      // list of files to exclude
      exclude: [
      ],
  
  
      // preprocess matching files before serving them to the browser
      // available preprocessors: https://npmjs.org/browse/keyword/karma-preprocessor
      preprocessors: {
              'src/*.js': ['babel']
      },
          'babelPreprocessor': {
        options: {
          sourceMap: 'inline'
        },
        filename: function(file) {
          return file.originalPath.replace(/\.js$/, '.es5.js');
        },
        sourceFileName: function(file) {
          return file.originalPath;
        }
      },
  
  
  // test results reporter to use
  // possible values: 'dots', 'progress'
  // available reporters: https://npmjs.org/browse/keyword/karma-reporter
  reporters: ['progress'],
  </code></pre>
  
  <p><a href="https://github.com/pbrianmackey/ES6">Full project on github</a></p>
  
  <p>I am able to use many ES6 features including arrows.  Just no go on Generators.</p>