Add Float64Round operator.

test/unittests/compiler/machine-operator-unittest.cc

Index: test/unittests/compiler/machine-operator-unittest.cc
diff --git a/test/unittests/compiler/machine-operator-unittest.cc b/test/unittests/compiler/machine-operator-unittest.cc
index 9d66f9e47b98ae3cd8d005a810a933b5fcce4250..41ac5c1ca5abcb247f14dda5cdc117c4ad5f2fd8 100644
--- a/test/unittests/compiler/machine-operator-unittest.cc
+++ b/test/unittests/compiler/machine-operator-unittest.cc
@@ -202,7 +202,9 @@ const PureOperator kPureOperators[] = {
     PURE(Float64Div, 2, 1),               PURE(Float64Mod, 2, 1),
     PURE(Float64Sqrt, 1, 1),              PURE(Float64Equal, 2, 1),
     PURE(Float64LessThan, 2, 1),          PURE(Float64LessThanOrEqual, 2, 1),
-    PURE(LoadStackPointer, 0, 1)
+    PURE(LoadStackPointer, 0, 1),         PURE(Float64Floor, 1, 1),
+    PURE(Float64Ceil, 1, 1),              PURE(Float64RoundTruncate, 1, 1),
+    PURE(Float64RoundTiesAway, 1, 1),
 #undef PURE
 };