Expose native pointer thru an interface function for YogaConfig

Summary:
Expose native pointer thru an interface function for YogaConfig (its package private to `com.facebook.yoga` namespace),
This way we can make later on YogaConfig a pure abstract class.

Plus, it makes sure external users don't modify the pointer

Reviewed By: SidharthGuglani

Differential Revision: D17266401

fbshipit-source-id: f39b488cea0b73bc3578bb3aa90ab00139bf9271

ReactAndroid/src/main/java/com/facebook/yoga/YogaConfig.java

@@ -12,7 +12,7 @@ public class YogaConfig {
 
   public static int SPACING_TYPE = 1;
 
-  long mNativePointer;
+  private long mNativePointer;
   private YogaLogger mLogger;
   private YogaNodeCloneFunction mYogaNodeCloneFunction;
 
@@ -76,4 +76,8 @@ public class YogaConfig {
   public YogaLogger getLogger() {
     return mLogger;
   }
+
+  long getNativePointer() {
+    return mNativePointer;
+  }
 }

ReactAndroid/src/main/java/com/facebook/yoga/YogaNodeJNIBase.java

@@ -58,7 +58,7 @@ public abstract class YogaNodeJNIBase extends YogaNode implements Cloneable {
   }
 
   YogaNodeJNIBase(YogaConfig config) {
-    this(YogaNative.jni_YGNodeNewWithConfig(config.mNativePointer));
+    this(YogaNative.jni_YGNodeNewWithConfig(config.getNativePointer()));
   }
 
   public void reset() {