es5-shim: Add polyfill for Object.create

Follows-up fff9a814f2327eb. Per the OOjs readme, it requires:

> (..) parser compatibility with ES3 engines.
> To support ES3 engines, ensure an appropriate polyfill is
> loaded for these methods:
> * Array.isArray
> * Object.create (basic use only)
> * Object.keys
> * JSON.stringify

The es5-shim and oojs modules already provide JSON, and most
Array and Object methods. Except for Object.create because there
are a few features in it that can't be emulated, and hence
es5-shim refuses to ship the polyfill for it.

Bug: 67590
Change-Id: I4838d78f77a3a71f80e6750adb914213b5ca4df5

diff --git a/resources/Resources.php b/resources/Resources.php
index 99e1e4f..29c74ee 100644 (file)
--- a/resources/Resources.php
+++ b/resources/Resources.php
@@ -1500,6 +1500,7 @@ return array(
        'es5-shim' => array(
                'scripts' => array(
                        'resources/lib/es5-shim/es5-shim.js',
+                       'resources/src/polyfill-object-create.js',
                ),
                'targets' => array( 'desktop', 'mobile' ),
                'skipFunction' => 'resources/src/es5-skip.js',

diff --git a/resources/src/polyfill-object-create.js b/resources/src/polyfill-object-create.js
new file mode 100644 (file)
index 0000000..607faf6
--- /dev/null
+++ b/resources/src/polyfill-object-create.js
@@ -0,0 +1,62 @@
+/**
+ * Simplified version of es5-sham#Object-create that also works around a bug
+ * in the actual es5-sham: https://github.com/es-shims/es5-shim/issues/252
+ *
+ * Does not:
+ * - Support empty inheritance via `Object.create(null)`.
+ * - Support getter and setter accessors via `Object.create( .., properties )`.
+ * - Support custom property descriptor (e.g. writable, configurtable, enumerable).
+ * - Leave behind an enumerable "__proto__" all over the place.
+ *
+ * @author Timo Tijhof, 2014
+ */
+
+// ES5 15.2.3.5
+// http://es5.github.com/#x15.2.3.5
+if ( !Object.create ) {
+       ( function () {
+               var hasOwn = Object.hasOwnProperty,
+                       // https://developer.mozilla.org/en-US/docs/ECMAScript_DontEnum_attribute#JScript_DontEnum_Bug
+                       // http://whattheheadsaid.com/2010/10/a-safer-object-keys-compatibility-implementation
+                       isEnumBug = !{ valueOf: 0 }.propertyIsEnumerable( 'valueOf' );
+
+               // Reusable constructor function for Object.create
+               function Empty() {}
+
+               function defineProperty( object, key, property ) {
+                       if ( hasOwn.call( property, 'value' ) ) {
+                               object[ key ] = property.value;
+                       } else {
+                               object[ key ] = property;
+                       }
+               }
+
+               Object.create = function create( prototype, properties ) {
+                       var object, key;
+
+                       if ( prototype !== Object( prototype ) ) {
+                               throw new TypeError( 'Called on non-object' );
+                       }
+
+                       Empty.prototype = prototype;
+                       object = new Empty();
+
+                       if ( properties !== undefined ) {
+                               if ( !isEnumBug ) {
+                                       for ( key in properties ) {
+                                               if ( hasOwn.call( properties, key ) ) {
+                                                       defineProperty( object, key, properties[ key ] );
+                                               }
+                                       }
+                               } else {
+                                       Object.keys( properties ).forEach( function ( key ) {
+                                               defineProperty( object, key, properties[ key ] );
+                                       } );
+                               }
+                       }
+
+                       return object;
+               };
+
+       }() );
+}