Create a module for React Native to get IsRTL info and set ForceRTL 2/2

Summary: This diff build the connection between the native code and js code so that the js could get IsRTL value and us ForceRTL function.

Reviewed By: fkgozali

Differential Revision: D3447013

fbshipit-source-id: 9f6c7f71cef0add7bd5beb0ba2b1543f0cabc2b3

React/Views/RCTRootShadowView.m

@@ -7,10 +7,26 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  */
 
+#import "RCTI18nUtil.h"
 #import "RCTRootShadowView.h"
 
 @implementation RCTRootShadowView
 
+/**
+ * Init the RCTRootShadowView with RTL status.
+ * Returns a RTL CSS layout if isRTL is true (Default is LTR CSS layout).
+ */
+- (instancetype)init
+{
+  self = [super init];
+  if (self) {
+    if ([[RCTI18nUtil sharedInstance] isRTL]) {
+      self.cssNode->style.direction = CSS_DIRECTION_RTL;
+    }
+  }
+  return self;
+}
+
 - (void)applySizeConstraints
 {
   switch (_sizeFlexibility) {