Fix behaviour of freeNatives()

Summary:
@public

Prevents repeated deallocation of weak references.

Reviewed By: pasqualeanatriello

Differential Revision: D9131551

fbshipit-source-id: bc79596e056ae0657a55146ad786422fd0f5badc

java/com/facebook/yoga/YogaNodePropertiesByteBuffer.java

@@ -25,6 +25,7 @@ public class YogaNodePropertiesByteBuffer implements YogaNodeProperties, Cloneab
   private final long mNativePointer;
   private boolean mHasBorderSet = false;
   private boolean mHasNewLayout = true;
+  private boolean isFreed = false;
 
   private static native ByteBuffer jni_getStyleBuffer(long nativePointer);
 
@@ -48,12 +49,10 @@ public class YogaNodePropertiesByteBuffer implements YogaNodeProperties, Cloneab
     mLayoutBuffer = jni_getLayoutBuffer(nativePointer).order(ByteOrder.LITTLE_ENDIAN);
   }
 
-  private static native void jni_YGNodeFree(long nativePointer);
-
   @Override
   protected void finalize() throws Throwable {
     try {
-      jni_YGNodeFree(getNativePointer());
+      freeNatives();
     } finally {
       super.finalize();
     }
@@ -482,9 +481,14 @@ public class YogaNodePropertiesByteBuffer implements YogaNodeProperties, Cloneab
     return YogaDirection.fromInt(getLayoutDirectionInt());
   }
 
+  private static native void jni_YGNodeFree(long nativePointer);
+
   @Override
   public void freeNatives() {
-    jni_YGNodeFree(mNativePointer);
+    if (!isFreed) {
+      isFreed = true;
+      jni_YGNodeFree(mNativePointer);
+    }
   }
 
   private int getLayoutDirectionInt() {

java/com/facebook/yoga/YogaNodePropertiesJNI.java

@@ -66,12 +66,13 @@ public class YogaNodePropertiesJNI implements Cloneable, YogaNodeProperties {
     }
   }
 
-  private native void jni_YGNodeFree(long nativePointer);
+  private static native void jni_YGNodeFree(long nativePointer);
 
   @Override
   public void freeNatives() {
-    jni_YGNodeFree(mNativePointer);
+    long nativePointer = mNativePointer;
     mNativePointer = 0;
+    jni_YGNodeFree(nativePointer);
   }
 
   @Override