Fix for Issue #6109 - aria-current has incorrect value "true" (#6118)

* Added 'false' as a valid value for aria-current in NavLink. Also made the default value 'page' instead of 'true'.

* Remove "false" string as a permitted aria-current value.

packages/react-router-dom/modules/NavLink.js

@@ -73,7 +73,7 @@ NavLink.propTypes = {
 
 NavLink.defaultProps = {
   activeClassName: "active",
-  "aria-current": "true"
+  "aria-current": "page"
 };
 
 export default NavLink;

packages/react-router-dom/modules/__tests__/NavLink-test.js

@@ -53,7 +53,7 @@ describe("NavLink", () => {
       expect(a.style.color).toBe(activeStyle.color);
     });
 
-    it("applies aria-current of true if no override value is given", () => {
+    it("applies aria-current of page if no override value is given", () => {
       ReactDOM.render(
         <MemoryRouter initialEntries={["/pizza"]}>
           <NavLink to="/pizza" activeClassName="selected">
@@ -63,20 +63,20 @@ describe("NavLink", () => {
         node
       );
       const a = node.getElementsByTagName("a")[0];
-      expect(a.getAttribute("aria-current")).toEqual("true");
+      expect(a.getAttribute("aria-current")).toEqual("page");
     });
 
     it("applies the override aria-current value when given", () => {
       ReactDOM.render(
         <MemoryRouter initialEntries={["/pizza"]}>
-          <NavLink to="/pizza" activeClassName="selected" aria-current="page">
+          <NavLink to="/pizza" activeClassName="selected" aria-current="true">
             Pizza!
           </NavLink>
         </MemoryRouter>,
         node
       );
       const a = node.getElementsByTagName("a")[0];
-      expect(a.getAttribute("aria-current")).toEqual("page");
+      expect(a.getAttribute("aria-current")).toEqual("true");
     });
 
     it("handles locations without a pathname", () => {