Add suppressContentEditableWarning to react

* react: add support for the new suppressContentEditableWarning flag
https://github.com/facebook/react/pull/6112

react/index.d.ts

@@ -2042,6 +2042,7 @@ declare namespace React {
         // React-specific Attributes
         defaultChecked?: boolean;
         defaultValue?: string | string[];
+        suppressContentEditableWarning?: boolean;
 
         // Standard HTML Attributes
         accept?: string;

react/test/tsx.tsx

@@ -33,3 +33,13 @@ StatelessComponent2.defaultProps = {
         <div slot="Some Div"> Hello again! </div>
     </g>
 </svg>;
+
+// React-specific Attributes
+<div
+    defaultChecked
+    defaultValue="some value"
+    contentEditable
+    suppressContentEditableWarning
+    >
+    <b>foo</b>
+</div>