[turbofan] Support lowering of ChangeFloat64ToTagged/ChangeTaggedToInt32.

src/compiler/common-operator.h

Index: src/compiler/common-operator.h
diff --git a/src/compiler/common-operator.h b/src/compiler/common-operator.h
index 2c5f1b66fc7dcc3d2174918c0aa8387d5954fa84..0b51088ca6967d2836f83a8c8ca92ba68efc5d44 100644
--- a/src/compiler/common-operator.h
+++ b/src/compiler/common-operator.h
@@ -134,6 +134,11 @@ class CommonOperatorBuilder {
     return new (zone_) SimpleOperator(IrOpcode::kControlEffect, Operator::kPure,
                                       0, 0, "ControlEffect");
   }
+  Operator* ValueEffect(int arguments) {
+    DCHECK(arguments > 0);  // Disallow empty value effects.
+    return new (zone_) SimpleOperator(IrOpcode::kValueEffect, Operator::kPure,
+                                      arguments, 0, "ValueEffect");
+  }
   Operator* Finish(int arguments) {
     DCHECK(arguments > 0);  // Disallow empty finishes.
     return new (zone_) Operator1<int>(IrOpcode::kFinish, Operator::kPure, 1, 1,