Proposed fix for systemjs#919

- Fix code in cjs.js to correctly match last index of comments.
- Add test module that includes the require('') at end of comment string
- Add unit test to prove the module can be loaded OK with the comment present

lib/cjs.js

@@ -24,7 +24,7 @@
     function inLocation(locations, match, starts) {
       var inLocation = false;
       for (var i = 0; i < locations.length; i++)
-        if (locations[i][0] < match.index && locations[i][1] > match.index + (!starts ? match[0].length : 0))
+        if (locations[i][0] < match.index && locations[i][1] > match.index + (!starts ? (match[0].length - 1) : 0))
           return true;
       return false;
     }

test/test.js

@@ -338,6 +338,13 @@ asyncTest('CommonJS detection variation 1', function() {
   }, err);
 });
 
+asyncTest('CommonJS module with require at end of comment loads OK', function() {
+  System['import']('tests/commonjs-requires-in-comment.js').then(function(m) {
+    ok(m);
+    start();
+  }, err);
+});
+
 if (!ie8)
 asyncTest('CommonJS detection variation 2', function() {
   System['import']('tests/commonjs-variation2.js').then(function(m) {

test/tests/commonjs-requires-in-comment.js

@@ -0,0 +1,15 @@
+"format cjs";
+
+System.register("lib/module-with-comment", [], function($__export) {
+  "use strict";
+  var __moduleName = "lib/module-with-comment";
+  var shared;
+  return {
+  	// This comment triggered SystemJS to do a require because of this -> require('')
+    setters: [function(m) {
+      shared = m.default;
+    }],
+    execute: function() {
+    }
+  };
+});