Dynamic Text Sizes for Text component

Summary:
Dynamic Text Sizes for Text component.
Text gains new prop - allowFontScaling (false by default).
There is also AccessibilityManager module that allows you to tune multipliers per each content size category.

Examples/UIExplorer/TextExample.ios.js

@@ -378,6 +378,25 @@ exports.examples = [
       </View>
     );
   },
+}, {
+  title: 'allowFontScaling attribute',
+  render: function() {
+    return (
+      <View>
+        <Text>
+          By default, text will respect Text Size accessibility setting on iOS.
+          It means that all font sizes will be increased or descreased depending on the value of Text Size setting in
+          {" "}<Text style={{fontWeight: 'bold'}}>Settings.app - Display & Brightness - Text Size</Text>
+        </Text>
+        <Text style={{marginTop: 10}}>
+          You can disable scaling for your Text component by passing {"\""}allowFontScaling={"{"}false{"}\""} prop.
+        </Text>
+        <Text allowFontScaling={false} style={{marginTop: 20}}>
+          This text will not scale.
+        </Text>
+      </View>
+    );
+  },
 }];
 
 var styles = StyleSheet.create({