[turbofan] Make FrameStateBeforeAndAfter explicit.

src/compiler/bytecode-graph-builder.h

Index: src/compiler/bytecode-graph-builder.h
diff --git a/src/compiler/bytecode-graph-builder.h b/src/compiler/bytecode-graph-builder.h
index c0a4a1e1b224ceb5cdd8fcbf3c72783ad73824ba..53e77a86f11b3ea9cdb3a5cc44ec4c600ed8890a 100644
--- a/src/compiler/bytecode-graph-builder.h
+++ b/src/compiler/bytecode-graph-builder.h
@@ -37,7 +37,6 @@ class BytecodeGraphBuilder {
 
  private:
   class Environment;
-  class FrameStateBeforeAndAfter;
 
   void VisitBytecodes();
 
@@ -120,11 +119,20 @@ class BytecodeGraphBuilder {
                                     interpreter::Register first_arg,
                                     size_t arity);
 
+  // Prepare information for eager deoptimization. This information is carried
+  // by dedicated {Checkpoint} nodes that are wired into the effect chain.
+  // Conceptually this frame state is "before" a given operation.
+  void PrepareEagerCheckpoint();
+
+  // Prepare information for lazy deoptimization. This information is attached
+  // to the given node and the output value produced by the node is combined.
+  // Conceptually this frame state is "after" a given operation.
+  void PrepareFrameState(Node* node, OutputFrameStateCombine combine);
+
   // Computes register liveness and replaces dead ones in frame states with the
   // undefined values.
   void ClearNonLiveSlotsInFrameStates();
 
-  void BuildCreateLiteral(const Operator* op);
   void BuildCreateArguments(CreateArgumentsType type);
   Node* BuildLoadContextSlot();
   Node* BuildLoadGlobal(uint32_t feedback_slot_index, TypeofMode typeof_mode);