From 065a93290fb38b1739d29c764638b83a4e59c196 Mon Sep 17 00:00:00 2001
From: Jay Phelps <hello@jayphelps.com>
Date: Wed, 27 May 2015 16:54:19 -0700
Subject: [PATCH] [WIP] detect props that aren't writable, fixes
 emberjs/ember.js#11221

---
 packages/dom-helper/lib/prop.js | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/packages/dom-helper/lib/prop.js b/packages/dom-helper/lib/prop.js
index 8268cfad..be2e36dc 100644
--- a/packages/dom-helper/lib/prop.js
+++ b/packages/dom-helper/lib/prop.js
@@ -2,6 +2,9 @@ export function isAttrRemovalValue(value) {
   return value === null || value === undefined;
 }
 
+var getOwnPropertyDescriptor = Object.getOwnPropertyDescriptor;
+function UNDEFINED() {}
+
 // TODO should this be an o_create kind of thing?
 export var propertyCaches = {};
 
@@ -13,11 +16,26 @@ export function normalizeProperty(element, attrName) {
     // TODO should this be an o_create kind of thing?
     cache = {};
     for (key in element) {
-      cache[key.toLowerCase()] = key;
+      if (isSettable(element, key)) {
+        cache[key.toLowerCase()] = key;
+      } else {
+        cache[key] = UNDEFINED;
+      }
     }
     propertyCaches[tagName] = cache;
   }
 
   // presumes that the attrName has been lowercased.
-  return cache[attrName];
+  var value = cache[attrName];
+  return value === UNDEFINED ? undefined : value;
+}
+
+function isSettable(element, attrName) {
+  var desc = getOwnPropertyDescriptor(element.constructor.prototype, attrName);
+  if (!desc) { return true; }
+  if (desc.writable === false || !desc.hasOwnProperty('value') && typeof desc.set !== 'function') {
+    return false;
+  }
+
+  return true;
 }