Fixed #1750 cannot place slabs against blocks

Author: shoghicp

src/pocketmine/block/Slab.php

@@ -94,7 +94,7 @@ public function place(Item $item, Block $block, Block $target, $face, $fx, $fy,
 				return true;
 			}
 			//TODO: check for collision
-		}elseif(!($player instanceof Player)){
+		}else{
 			if($block->getID() === self::SLAB){
 				if(($block->getDamage() & 0x07) === ($this->meta & 0x07)){
 					$this->getLevel()->setBlock($block, Block::get(Item::DOUBLE_SLAB, $this->meta), true);
@@ -108,9 +108,8 @@ public function place(Item $item, Block $block, Block $target, $face, $fx, $fy,
 					$this->meta |= 0x08;
 				}
 			}
-		}else{
-			return false;
 		}
+
 		if($block->getID() === self::SLAB and ($target->getDamage() & 0x07) !== ($this->meta & 0x07)){
 			return false;
 		}

src/pocketmine/block/WoodSlab.php

@@ -91,7 +91,7 @@ public function place(Item $item, Block $block, Block $target, $face, $fx, $fy,
 
 				return true;
 			}
-		}elseif(!($player instanceof Player)){ //TODO: collision
+		}else{ //TODO: collision
 			if($block->getID() === self::WOOD_SLAB){
 				if(($block->getDamage() & 0x07) === ($this->meta & 0x07)){
 					$this->getLevel()->setBlock($block, Block::get(Item::DOUBLE_WOOD_SLAB, $this->meta), true);
@@ -105,9 +105,8 @@ public function place(Item $item, Block $block, Block $target, $face, $fx, $fy,
 					$this->meta |= 0x08;
 				}
 			}
-		}else{
-			return false;
 		}
+		
 		if($block->getID() === self::WOOD_SLAB and ($target->getDamage() & 0x07) !== ($this->meta & 0x07)){
 			return false;
 		}