fix(android/iOS): Fixed react-native 0.58 warnings (#311)

js/WebView.android.js

     );
   }
 
+  getCommands = () => UIManager.getViewManagerConfig('RNCWebView').Commands;
+
   goForward = () => {
     UIManager.dispatchViewManagerCommand(
       this.getWebViewHandle(),
-      UIManager.RNCWebView.Commands.goForward,
+      this.getCommands().goForward,
       null,
     );
   };
   goBack = () => {
     UIManager.dispatchViewManagerCommand(
       this.getWebViewHandle(),
-      UIManager.RNCWebView.Commands.goBack,
+      this.getCommands().goBack,
       null,
     );
   };
     });
     UIManager.dispatchViewManagerCommand(
       this.getWebViewHandle(),
-      UIManager.RNCWebView.Commands.reload,
+      this.getCommands().reload,
       null,
     );
   };
   stopLoading = () => {
     UIManager.dispatchViewManagerCommand(
       this.getWebViewHandle(),
-      UIManager.RNCWebView.Commands.stopLoading,
+      this.getCommands().stopLoading,
       null,
     );
   };
   postMessage = (data: string) => {
     UIManager.dispatchViewManagerCommand(
       this.getWebViewHandle(),
-      UIManager.RNCWebView.Commands.postMessage,
+      this.getCommands().postMessage,
       [String(data)],
     );
   };
   injectJavaScript = (data: string) => {
     UIManager.dispatchViewManagerCommand(
       this.getWebViewHandle(),
-      UIManager.RNCWebView.Commands.injectJavaScript,
+      this.getCommands().injectJavaScript,
       [data],
     );
   };
     if (shouldStart) {
       UIManager.dispatchViewManagerCommand(
         this.getWebViewHandle(),
-        UIManager.RNCWebView.Commands.loadUrl,
+        this.getCommands().loadUrl,
         [String(url)],
       );
     }

js/WebView.ios.js

     );
   }
 
-  _getCommands() {
-    if (!this.props.useWebKit) {
-      return UIManager.RNCUIWebView.Commands;
-    }
-
-    return UIManager.RNCWKWebView.Commands;
-  }
+  _getCommands = () =>
+    !this.props.useWebKit
+      ? UIManager.getViewManagerConfig('RNCUIWebView').Commands
+      : UIManager.getViewManagerConfig('RNCWKWebView').Commands;
 
   /**
    * Go forward one page in the web view's history.

package.json

     "flow-bin": "^0.80.0",
     "jest": "^24.0.0",
     "metro-react-native-babel-preset": "^0.51.1",
-    "react-native": "^0.57",
+    "react-native": ">=0.57 <0.59",
     "semantic-release": "15.10.3"
   },
   "repository": {