[turbofan] Initial attempt to cleanup Node and related classes.

src/compiler/common-operator.cc

Index: src/compiler/common-operator.cc
diff --git a/src/compiler/common-operator.cc b/src/compiler/common-operator.cc
index 54059ac29a6f09bf11f098d528315ec1f7815776..e7d583f831df475fae0edbd4f6c37f36acea7b8c 100644
--- a/src/compiler/common-operator.cc
+++ b/src/compiler/common-operator.cc
@@ -103,6 +103,12 @@ std::ostream& operator<<(std::ostream& os, FrameStateCallInfo const& info) {
 }
 
 
+size_t ProjectionIndexOf(const Operator* const op) {
+  DCHECK_EQ(IrOpcode::kProjection, op->opcode());
+  return OpParameter<size_t>(op);
+}
+
+
 #define CACHED_OP_LIST(V)                                  \
   V(Dead, Operator::kFoldable, 0, 0, 0, 0, 0, 1)           \
   V(End, Operator::kFoldable, 0, 0, 1, 0, 0, 0)            \