chore(build): remove references to e6-module-loader

I believe that it is no longer necessery after migration
to a newer version of SystemJS

Closes #3752

tools/broccoli/html-replace/SCRIPTS.html

@@ -1,7 +1,6 @@
 <script src="zone-microtask.js" type="text/javascript"></script>
 <script src="long-stack-trace-zone.js" type="text/javascript"></script>
 <script src="traceur-runtime.js" type="text/javascript"></script>
-<script src="es6-module-loader-sans-promises.src.js" type="text/javascript"></script>
 <script src="system.src.js" type="text/javascript"></script>
 <script src="Reflect.js" type="text/javascript"></script>
 <script type="text/javascript">

tools/broccoli/html-replace/SCRIPTS_benchmarks.html

@@ -2,7 +2,6 @@
 <script src="long-stack-trace-zone.js" type="text/javascript"></script>
 <script src="url_params_to_form.js" type="text/javascript"></script>
 <script src="traceur-runtime.js" type="text/javascript"></script>
-<script src="es6-module-loader-sans-promises.src.js" type="text/javascript"></script>
 <script src="system.src.js" type="text/javascript"></script>
 <script src="Reflect.js" type="text/javascript"></script>
 <script type="text/javascript">

tools/broccoli/html-replace/SCRIPTS_benchmarks_external.html

@@ -3,7 +3,6 @@
 <script src="angular.js" type="text/javascript"></script>
 <script src="url_params_to_form.js" type="text/javascript"></script>
 <script src="traceur-runtime.js" type="text/javascript"></script>
-<script src="es6-module-loader-sans-promises.src.js" type="text/javascript"></script>
 <script src="system.src.js" type="text/javascript"></script>
 <script src="Reflect.js" type="text/javascript"></script>
 <script type="text/javascript">