SPIGOT-5826: Don't store chunk in block states

src/main/java/org/bukkit/craftbukkit/block/CraftBlockState.java

@@ -23,7 +23,6 @@ import org.bukkit.plugin.Plugin;
 
 public class CraftBlockState implements BlockState {
     protected final CraftWorld world;
-    private final CraftChunk chunk;
     private final BlockPosition position;
     protected IBlockData data;
     protected int flag;
@@ -32,7 +31,6 @@ public class CraftBlockState implements BlockState {
         this.world = (CraftWorld) block.getWorld();
         this.position = ((CraftBlock) block).getPosition();
         this.data = ((CraftBlock) block).getNMS();
-        this.chunk = (CraftChunk) block.getChunk();
         this.flag = 3;
     }
 
@@ -44,7 +42,6 @@ public class CraftBlockState implements BlockState {
     public CraftBlockState(Material material) {
         world = null;
         data = CraftMagicNumbers.getBlock(material).getBlockData();
-        chunk = null;
         position = BlockPosition.ZERO;
     }
 
@@ -80,7 +77,7 @@ public class CraftBlockState implements BlockState {
     @Override
     public Chunk getChunk() {
         requirePlaced();
-        return chunk;
+        return world.getChunkAt(getX() >> 4, getZ() >> 4);
     }
 
     public void setData(IBlockData data) {
@@ -263,25 +260,25 @@ public class CraftBlockState implements BlockState {
     @Override
     public void setMetadata(String metadataKey, MetadataValue newMetadataValue) {
         requirePlaced();
-        chunk.getCraftWorld().getBlockMetadata().setMetadata(getBlock(), metadataKey, newMetadataValue);
+        world.getBlockMetadata().setMetadata(getBlock(), metadataKey, newMetadataValue);
     }
 
     @Override
     public List<MetadataValue> getMetadata(String metadataKey) {
         requirePlaced();
-        return chunk.getCraftWorld().getBlockMetadata().getMetadata(getBlock(), metadataKey);
+        return world.getBlockMetadata().getMetadata(getBlock(), metadataKey);
     }
 
     @Override
     public boolean hasMetadata(String metadataKey) {
         requirePlaced();
-        return chunk.getCraftWorld().getBlockMetadata().hasMetadata(getBlock(), metadataKey);
+        return world.getBlockMetadata().hasMetadata(getBlock(), metadataKey);
     }
 
     @Override
     public void removeMetadata(String metadataKey, Plugin owningPlugin) {
         requirePlaced();
-        chunk.getCraftWorld().getBlockMetadata().removeMetadata(getBlock(), metadataKey, owningPlugin);
+        world.getBlockMetadata().removeMetadata(getBlock(), metadataKey, owningPlugin);
     }
 
     @Override