Merge pull request facebook#5093 from jimfb/avoid-children-to-string-coercion

Should not coerce children prop on custom elements to a string.  Fixes facebook#5088
(cherry picked from commit a2d26c8)

Author: jimfb

src/renderers/dom/shared/ReactDOMComponent.js

@@ -51,6 +51,7 @@ var registrationNameModules = ReactBrowserEventEmitter.registrationNameModules;
 // For quickly matching children type, to test if can be treated as content.
 var CONTENT_TYPES = {'string': true, 'number': true};
 
+var CHILDREN = keyOf({children: null});
 var STYLE = keyOf({style: null});
 var HTML = keyOf({__html: null});
 
@@ -675,7 +676,9 @@ ReactDOMComponent.Mixin = {
         }
         var markup = null;
         if (this._tag != null && isCustomComponent(this._tag, props)) {
-          markup = DOMPropertyOperations.createMarkupForCustomAttribute(propKey, propValue);
+          if (propKey !== CHILDREN) {
+            markup = DOMPropertyOperations.createMarkupForCustomAttribute(propKey, propValue);
+          }
         } else {
           markup = DOMPropertyOperations.createMarkupForProperty(propKey, propValue);
         }
@@ -962,6 +965,9 @@ ReactDOMComponent.Mixin = {
         if (!node) {
           node = ReactMount.getNode(this._rootNodeID);
         }
+        if (propKey === CHILDREN) {
+          nextProp = null;
+        }
         DOMPropertyOperations.setValueForAttribute(
           node,
           propKey,

src/renderers/dom/shared/__tests__/ReactDOMComponent-test.js

@@ -198,6 +198,18 @@ describe('ReactDOMComponent', function() {
       expect(stubStyle.display).toEqual('');
     });
 
+    it('should skip child object attribute on web components', function() {
+      var container = document.createElement('div');
+
+      // Test intial render to null
+      ReactDOM.render(<my-component children={['foo']} />, container);
+      expect(container.firstChild.hasAttribute('children')).toBe(false);
+
+      // Test updates to null
+      ReactDOM.render(<my-component children={['foo']} />, container);
+      expect(container.firstChild.hasAttribute('children')).toBe(false);
+    });
+
     it('should remove attributes', function() {
       var container = document.createElement('div');
       ReactDOM.render(<img height="17" />, container);