[turbofan] Unify Math.floor / Math.ceil optimization.

src/compiler/raw-machine-assembler.h

Index: src/compiler/raw-machine-assembler.h
diff --git a/src/compiler/raw-machine-assembler.h b/src/compiler/raw-machine-assembler.h
index b578aca73f767726ff4c090601a00fbe8dd7e216..82ef3fabf2297490045baa116d15fdc78554081a 100644
--- a/src/compiler/raw-machine-assembler.h
+++ b/src/compiler/raw-machine-assembler.h
@@ -390,8 +390,9 @@ class RawMachineAssembler : public GraphBuilder {
   Node* TruncateInt64ToInt32(Node* a) {
     return NewNode(machine()->TruncateInt64ToInt32(), a);
   }
-  Node* Float64Floor(Node* a) { return NewNode(machine()->Float64Floor(), a); }
-  Node* Float64Ceil(Node* a) { return NewNode(machine()->Float64Ceil(), a); }
+  Node* Float64RoundDown(Node* a) {
+    return NewNode(machine()->Float64RoundDown(), a);
+  }
   Node* Float64RoundTruncate(Node* a) {
     return NewNode(machine()->Float64RoundTruncate(), a);
   }