Check for addEventListener before tying to use to support IE 8

Author: amccloud

Diff for: lib/helpers/focusManager.js

@@ -40,13 +40,26 @@ exports.returnFocus = function() {
 
 exports.setupScopedFocus = function(element) {
   modalElement = element;
-  window.addEventListener('blur', handleBlur, false);
-  document.addEventListener('focus', handleFocus, true);
+
+  if (window.addEventListener) {
+    window.addEventListener('blur', handleBlur, false);
+    document.addEventListener('focus', handleFocus, true);
+  } else {
+    window.attachEvent('onBlur', handleBlur);
+    document.attachEvent('onFocus', handleFocus);
+  }
 };
 
 exports.teardownScopedFocus = function() {
   modalElement = null;
-  window.removeEventListener('blur', handleBlur);
-  document.removeEventListener('focus', handleFocus);
+
+  if (window.addEventListener) {
+    window.removeEventListener('blur', handleBlur);
+    document.removeEventListener('focus', handleFocus);
+  } else {
+    window.detachEvent('onBlur', handleBlur);
+    document.detachEvent('onFocus', handleFocus);
+  }
 };
 
+