[turbofan] Move graph trimming functionality to dedicated GraphTrimmer.

src/compiler/graph-reducer.h

Index: src/compiler/graph-reducer.h
diff --git a/src/compiler/graph-reducer.h b/src/compiler/graph-reducer.h
index a8a907fa12731b29b0834d9fa207a565d371e6b2..b4e9ef8d1ccedb7c414d63a4f79e1b06d0b5fdd4 100644
--- a/src/compiler/graph-reducer.h
+++ b/src/compiler/graph-reducer.h
@@ -47,13 +47,6 @@ class Reducer {
   // Try to reduce a node if possible.
   virtual Reduction Reduce(Node* node) = 0;
 
-  // Ask this reducer to finish operation, returns {true} if the reducer is
-  // done, while {false} indicates that the graph might need to be reduced
-  // again.
-  // TODO(turbofan): Remove this once the dead node trimming is in the
-  // GraphReducer.
-  virtual bool Finish();
-
   // Helper functions for subclasses to produce reductions for a node.
   static Reduction NoChange() { return Reduction(); }
   static Reduction Replace(Node* node) { return Reduction(node); }