Fix buggy DOM nesting warning for text components

cf. #5071

src/renderers/dom/shared/ReactDOMTextComponent.js

@@ -93,7 +93,7 @@ assign(ReactDOMTextComponent.prototype, {
       if (parentInfo) {
         // parentInfo should always be present except for the top-level
         // component when server rendering
-        validateDOMNesting(this._tag, this, parentInfo);
+        validateDOMNesting('span', this, parentInfo);
       }
     }
 

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

@@ -926,17 +926,21 @@ describe('ReactDOMComponent', function() {
       });
       var Foo = React.createClass({
         render: function() {
-          return <table><Row /></table>;
+          return <table><Row /> </table>;
         },
       });
       ReactTestUtils.renderIntoDocument(<Foo />);
 
-      expect(console.error.calls.length).toBe(1);
+      expect(console.error.calls.length).toBe(2);
       expect(console.error.argsForCall[0][0]).toBe(
         'Warning: validateDOMNesting(...): <tr> cannot appear as a child of ' +
         '<table>. See Foo > table > Row > tr. Add a <tbody> to your code to ' +
         'match the DOM tree generated by the browser.'
       );
+      expect(console.error.argsForCall[1][0]).toBe(
+        'Warning: validateDOMNesting(...): <span> cannot appear as a child ' +
+        'of <table>. See Foo > table > span.'
+      );
     });
 
     it('gives useful context in warnings', () => {