util.defineSecureProp() no longer performs fallback check on each invocation

lib/util.js

@@ -80,6 +80,8 @@ exports.secureFallback = function( val )
     }
 
     secure_fallback = !!val;
+    exports.defineSecureProp = getDefineSecureProp();
+
     return exports;
 };
 
@@ -96,32 +98,7 @@ exports.secureFallback = function( val )
  *
  * @return  {undefined}
  */
-exports.defineSecureProp = function( obj, prop, value )
+exports.defineSecureProp = getDefineSecureProp();
-{
-    if ( secure_fallback )
-    {
-        obj[ prop ] = value;
-    }
-    else
-    {
-        try
-        {
-            Object.defineProperty( obj, prop,
-            {
-                value: value,
-
-                enumerable:   false,
-                writable:     false,
-                configurable: false,
-            });
-        }
-        catch ( e )
-        {
-            // if there's an error (ehem, IE8), fall back
-            obj[ prop ] = value;
-        }
-    }
-}
 
 
 /**
@@ -479,3 +456,47 @@ exports.arrayShrink = function( items )
     return arr_new;
 }
 
+
+/**
+ * Appropriately returns defineSecureProp implementation to avoid check on each
+ * invocation
+ *
+ * @return  {function( Object, string, * )}
+ */
+function getDefineSecureProp()
+{
+    // falls back to simply defining a normal property
+    var fallback = function( obj, prop, value )
+    {
+        obj[ prop ] = value;
+    };
+
+    if ( secure_fallback )
+    {
+        return fallback;
+    }
+    else
+    {
+        // uses ECMAScript 5's Object.defineProperty() method
+        return function( obj, prop, value )
+        {
+            try
+            {
+                Object.defineProperty( obj, prop,
+                {
+                    value: value,
+
+                    enumerable:   false,
+                    writable:     false,
+                    configurable: false,
+                });
+            }
+            catch ( e )
+            {
+                // if there's an error (ehem, IE8), fall back
+                fallback( obj, prop, value );
+            }
+        };
+    }
+}
+