Make react-router-dom treeshakable

packages/react-router-dom/.size-snapshot.json

@@ -1,26 +1,26 @@
 {
   "esm/react-router-dom.js": {
-    "bundled": 7978,
-    "minified": 4880,
-    "gzipped": 1618,
+    "bundled": 8022,
+    "minified": 4817,
+    "gzipped": 1612,
     "treeshaked": {
       "rollup": {
-        "code": 1250,
+        "code": 453,
         "import_statements": 417
       },
       "webpack": {
-        "code": 3322
+        "code": 1661
       }
     }
   },
   "umd/react-router-dom.js": {
-    "bundled": 159709,
-    "minified": 57597,
-    "gzipped": 16540
+    "bundled": 126991,
+    "minified": 47032,
+    "gzipped": 14084
   },
   "umd/react-router-dom.min.js": {
-    "bundled": 97476,
-    "minified": 34651,
-    "gzipped": 10216
+    "bundled": 84909,
+    "minified": 30118,
+    "gzipped": 9978
   }
 }

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

@@ -12,10 +12,6 @@ function isModifiedEvent(event) {
  * The public API for rendering a history-aware <a>.
  */
 class Link extends React.Component {
-  static defaultProps = {
-    replace: false
-  };
-
   handleClick(event, history) {
     if (this.props.onClick) this.props.onClick(event);
 

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

@@ -12,8 +12,8 @@ function joinClassnames(...classnames) {
  * A <Link> wrapper that knows if it's "active" or not.
  */
 function NavLink({
-  "aria-current": ariaCurrent,
-  activeClassName,
+  "aria-current": ariaCurrent = "page",
+  activeClassName = "active",
   activeStyle,
   className: classNameProp,
   exact,
@@ -59,11 +59,6 @@ function NavLink({
   );
 }
 
-NavLink.defaultProps = {
-  "aria-current": "page",
-  activeClassName: "active"
-};
-
 if (__DEV__) {
   const ariaCurrentType = PropTypes.oneOf([
     "page",