Merge pull request #52 from react-native-community/cleaning-unused-state-and-will-mount

(Contains #51) Cleaning unused state and will mount

js/WebView.android.js

 type State = {|
   viewState: WebViewState,
   lastErrorEvent: ?WebViewError,
-  startInLoadingState: boolean,
 |};
 
 /**
   };
 
   state = {
-    viewState: WebViewState.IDLE,
+    viewState: this.props.startInLoadingState ? WebViewState.LOADING : WebViewState.IDLE,
     lastErrorEvent: null,
-    startInLoadingState: true,
   };
 
   webViewRef = React.createRef();
 
-  UNSAFE_componentWillMount() {
-    if (this.props.startInLoadingState) {
-      this.setState({ viewState: WebViewState.LOADING });
-    }
-  }
-
   render() {
     let otherView = null;
 

js/WebView.ios.js

 type State = {|
   viewState: WebViewState,
   lastErrorEvent: ?WebViewError,
-  startInLoadingState: boolean,
 |};
 
 const DataDetectorTypes = [
   };
 
   state = {
-    viewState: WebViewState.IDLE,
+    viewState: this.props.startInLoadingState ? WebViewState.LOADING : WebViewState.IDLE,
     lastErrorEvent: null,
-    startInLoadingState: true,
   };
 
   webViewRef = React.createRef();
 
   UNSAFE_componentWillMount() {
-    if (this.props.startInLoadingState) {
-      this.setState({ viewState: WebViewState.LOADING });
-    }
-
     if (
       this.props.useWebKit === true &&
       this.props.scalesPageToFit !== undefined