track: fixed issues from recent rework

app/node/block/block.cpp

@@ -36,8 +36,7 @@ const QString Block::kLengthInput = QStringLiteral("length_in");
 Block::Block() :
   previous_(nullptr),
   next_(nullptr),
-  track_(nullptr),
-  index_(-1)
+  track_(nullptr)
 {
   AddInput(kLengthInput, NodeValue::kRational, InputFlags(kInputFlagNotConnectable | kInputFlagNotKeyframable | kInputFlagHidden));
   SetInputProperty(kLengthInput, QStringLiteral("min"), QVariant::fromValue(rational(0, 1)));

app/node/block/block.h

@@ -104,16 +104,6 @@ public:
 
   virtual void Retranslate() override;
 
-  int index() const
-  {
-    return index_;
-  }
-
-  void set_index(int i)
-  {
-    index_ = i;
-  }
-
   virtual void InvalidateCache(const TimeRange& range, const QString& from, int element = -1, InvalidateCacheOptions options = InvalidateCacheOptions()) override;
 
   static const QString kLengthInput;
@@ -143,7 +133,6 @@ private:
   rational in_point_;
   rational out_point_;
   Track* track_;
-  int index_;
 
   rational last_length_;