[turbofan] Introduce simplified operator NumberAbs.

test/unittests/compiler/simplified-operator-reducer-unittest.cc

Index: test/unittests/compiler/simplified-operator-reducer-unittest.cc
diff --git a/test/unittests/compiler/simplified-operator-reducer-unittest.cc b/test/unittests/compiler/simplified-operator-reducer-unittest.cc
index f4d8bac70449ea6c1a7deb8e83f74d7d78c62fdf..f84b9bf825ae532451b2d9a661fef03e232dcfeb 100644
--- a/test/unittests/compiler/simplified-operator-reducer-unittest.cc
+++ b/test/unittests/compiler/simplified-operator-reducer-unittest.cc
@@ -399,6 +399,18 @@ TEST_F(SimplifiedOperatorReducerTest, CheckTaggedSignedWithNumberConstant) {
 }
 
 // -----------------------------------------------------------------------------
+// NumberAbs
+
+TEST_F(SimplifiedOperatorReducerTest, NumberAbsWithNumberConstant) {
+  TRACED_FOREACH(double, n, kFloat64Values) {
+    Reduction reduction =
+        Reduce(graph()->NewNode(simplified()->NumberAbs(), NumberConstant(n)));
+    ASSERT_TRUE(reduction.Changed());
+    EXPECT_THAT(reduction.replacement(), IsNumberConstant(std::fabs(n)));
+  }
+}
+
+// -----------------------------------------------------------------------------
 // ObjectIsSmi
 
 TEST_F(SimplifiedOperatorReducerTest, ObjectIsSmiWithChangeBitToTagged) {