[turbofan] Introduce NumberFloor simplified operator.

src/compiler/simplified-operator-reducer.h

Index: src/compiler/simplified-operator-reducer.h
diff --git a/src/compiler/simplified-operator-reducer.h b/src/compiler/simplified-operator-reducer.h
index 979a3d03995ef851f2772db3a8daded8fe48e2d0..cef6782e0d42511fe5831a0ac0667ac7c9a5707a 100644
--- a/src/compiler/simplified-operator-reducer.h
+++ b/src/compiler/simplified-operator-reducer.h
@@ -9,6 +9,10 @@
 
 namespace v8 {
 namespace internal {
+
+// Forward declarations.
+class TypeCache;
+
 namespace compiler {
 
 // Forward declarations.
@@ -25,6 +29,7 @@ class SimplifiedOperatorReducer final : public Reducer {
   Reduction Reduce(Node* node) final;
 
  private:
+  Reduction ReduceNumberFloor(Node* node);
   Reduction ReduceReferenceEqual(Node* node);
 
   Reduction Change(Node* node, const Operator* op, Node* a);
@@ -42,6 +47,7 @@ class SimplifiedOperatorReducer final : public Reducer {
   SimplifiedOperatorBuilder* simplified() const;
 
   JSGraph* const jsgraph_;
+  TypeCache const& type_cache_;
 
   DISALLOW_COPY_AND_ASSIGN(SimplifiedOperatorReducer);
 };