diff --git a/src/common.js b/src/common.js
index 205b577d3e..56acb54a7e 100644
--- a/src/common.js
+++ b/src/common.js
@@ -1340,12 +1340,12 @@
             if (this.is_leaf(domain)) {
                 return [domain];
             } else if (domoperator === undefined) {
-                return [domain_type].concat(Array.concat.apply([],
+                return [domain_type].concat([].concat.apply([],
                         domain.map(function(e) {
                             return this.merge(e, domain_type);
                         }.bind(this))));
             } else if (domain_type == domoperator) {
-                return Array.concat.apply([], domain.map(function(e) {
+                return [].concat.apply([], domain.map(function(e) {
                     return this.merge(e, domain_type);
                 }.bind(this)));
             } else {
diff --git a/src/sao.js b/src/sao.js
index f197509227..7b31ae7fb8 100644
--- a/src/sao.js
+++ b/src/sao.js
@@ -5,6 +5,37 @@ var Sao = {};
 (function() {
     'use strict';
 
+    // Browser compatibility: polyfill
+    if (!('contains' in String.prototype)) {
+        String.prototype.contains = function(str, startIndex) {
+            return -1 !== String.prototype.indexOf.call(this, str, startIndex);
+        };
+    }
+    if (!String.prototype.startsWith) {
+        Object.defineProperty(String.prototype, 'startsWith', {
+            enumerable: false,
+            configurable: false,
+            writable: false,
+            value: function(searchString, position) {
+                position = position || 0;
+                return this.indexOf(searchString, position) === position;
+            }
+        });
+    }
+    if (!String.prototype.endsWith) {
+        Object.defineProperty(String.prototype, 'endsWith', {
+            enumerable: false,
+            configurable: false,
+            writable: false,
+            value: function(searchString, position) {
+                position = position || this.length;
+                position = position - searchString.length;
+                var lastIndex = this.lastIndexOf(searchString);
+                return lastIndex !== -1 && lastIndex === position;
+            }
+        });
+    }
+
     Sao.error = function(title, message) {
         alert(title + '\n' + (message || ''));
     };