[WebView] Exposed scalesPageToFit UIWebView property

Summary:
Added the ``scalesPageToFit`` prop to ``WebView``. This allows ``UIWebView`` to handle user zoom and scale.
Closes https://github.com/facebook/react-native/pull/1631
Github Author: alvaromb <amedina@apsl.net>

Test Plan: Imported from GitHub, without a `Test Plan:` line.

Examples/UIExplorer/WebViewExample.js

@@ -43,6 +43,7 @@ var WebViewExample = React.createClass({
       backButtonEnabled: false,
       forwardButtonEnabled: false,
       loading: true,
+      scalesPageToFit: true,
     };
   },
 
@@ -97,6 +98,7 @@ var WebViewExample = React.createClass({
           javaScriptEnabledAndroid={true}
           onNavigationStateChange={this.onNavigationStateChange}
           startInLoadingState={true}
+          scalesPageToFit={this.state.scalesPageToFit}
         />
         <View style={styles.statusBar}>
           <Text style={styles.statusBarText}>{this.state.status}</Text>
@@ -124,6 +126,7 @@ var WebViewExample = React.createClass({
       url: navState.url,
       status: navState.title,
       loading: navState.loading,
+      scalesPageToFit: true
     });
   },
 

Libraries/Components/WebView/WebView.ios.js

@@ -95,6 +95,11 @@ var WebView = React.createClass({
      * Used for android only, JS is enabled by default for WebView on iOS
      */
     javaScriptEnabledAndroid: PropTypes.bool,
+    /**
+     * Used for iOS only, sets whether the webpage scales to fit the view and the
+     * user can change the scale
+     */
+    scalesPageToFit: PropTypes.bool,
   },
 
   getInitialState: function() {
@@ -155,6 +160,7 @@ var WebView = React.createClass({
         onLoadingStart={this.onLoadingStart}
         onLoadingFinish={this.onLoadingFinish}
         onLoadingError={this.onLoadingError}
+        scalesPageToFit={this.props.scalesPageToFit}
       />;
 
     return (

React/Views/RCTWebViewManager.m

@@ -30,6 +30,7 @@ RCT_REMAP_VIEW_PROPERTY(scrollEnabled, _webView.scrollView.scrollEnabled, BOOL);
 RCT_EXPORT_VIEW_PROPERTY(contentInset, UIEdgeInsets);
 RCT_EXPORT_VIEW_PROPERTY(automaticallyAdjustContentInsets, BOOL);
 RCT_EXPORT_VIEW_PROPERTY(shouldInjectAJAXHandler, BOOL);
+RCT_REMAP_VIEW_PROPERTY(scalesPageToFit, _webView.scalesPageToFit, BOOL);
 
 - (NSDictionary *)constantsToExport
 {