Partially revert type -> elementType

Author: eps1lon

packages/react-dom/src/server/ReactPartialRenderer.js

@@ -389,14 +389,14 @@ function createOpenTagMarkup(
   return ret;
 }
 
-function validateRenderResult(child, elementType) {
+function validateRenderResult(child, type) {
   if (child === undefined) {
     invariant(
       false,
       '%s(...): Nothing was returned from render. This usually means a ' +
         'return statement is missing. Or, to render nothing, ' +
         'return null.',
-      getComponentName(elementType) || 'Component',
+      getComponentName(type) || 'Component',
     );
   }
 }