Improve IE compatibility by ensuring the __proto__ chain always exists.

In conjunction with googlearchive/CustomElements@9b4c5df, helps address #217.
Polymer · Jul 30, 2013 · 62eb34b · 62eb34b
1 parent 5ab7b2f
commit 62eb34b
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Showing 2 changed files with 15 additions and 5 deletions.
diff --git a/src/declaration/polymer-element.js b/src/declaration/polymer-element.js
@@ -66,14 +66,17 @@
       // Potentially remove when spec bug is addressed.
       // https://www.w3.org/Bugs/Public/show_bug.cgi?id=21407
       this.addResolvePathApi();
-      // declarative features
-      this.desugar();
       // under ShadowDOMPolyfill, transforms to approximate missing CSS features
       if (window.ShadowDOMPolyfill) {
         Platform.ShadowCSS.shimStyling(this.templateContent(), name, extnds);
       }
       // register our custom element
       this.register(name);
+      // declarative features
+      // NOTE: make sure to desugar after calling register. Registration
+      // ensures the __proto__ chain exists on platforms that don't support it
+      // natively (IE10), and desugar uses the __proto__ chain.
+      this.desugar();
       // reference constructor in a global named by 'constructor' attribute    
       this.publishConstructor();
     },
@@ -132,7 +135,7 @@
     // make a fresh object that inherits from a prototype object
     inheritObject: function(prototype, name) {
       // copy inherited properties onto a new object
-      prototype[name] = extend({}, prototype.__proto__[name]);
+      prototype[name] = extend({}, Object.getPrototypeOf(prototype)[name]);
     },
     // register 'prototype' to custom element 'name', store constructor 
     register: function(name) { 

diff --git a/src/lib/super.js b/src/lib/super.js
@@ -38,7 +38,7 @@
         }
         // super prototype is either cached or we have to find it
         // by searching __proto__ (at the 'top')
-        memoizeSuper(caller, nom, Object.getPrototypeOf(this));
+        memoizeSuper(caller, nom, getPrototypeOf(this));
       }
       var _super = caller._super;
       if (!_super) {
@@ -61,7 +61,7 @@
       // look for an inherited prototype that implements name
       while (proto &&
           (!proto.hasOwnProperty(name) || proto[name] === caller)) {
-        proto = Object.getPrototypeOf(proto);
+        proto = getPrototypeOf(proto);
       }
       return proto;
     };
@@ -93,6 +93,13 @@
         p = p.__proto__;
       }
     }
+
+    // NOTE: In some platforms (IE10) the prototype chain is faked via 
+    // __proto__. Therefore, always get prototype via __proto__ instead of
+    // the more standard Object.getPrototypeOf.
+    function getPrototypeOf(prototype) {
+      return prototype.__proto__;
+    }
 
     // exports