Revert of [regexp] Remove IsRegExp intrinsic

test/cctest/interpreter/test-interpreter-intrinsics.cc

Index: test/cctest/interpreter/test-interpreter-intrinsics.cc
diff --git a/test/cctest/interpreter/test-interpreter-intrinsics.cc b/test/cctest/interpreter/test-interpreter-intrinsics.cc
index 70051253cca22fc04d4752559da6bfe25bae8ae3..3cb2beffd456e1624633018f04881291651bf2a9 100644
--- a/test/cctest/interpreter/test-interpreter-intrinsics.cc
+++ b/test/cctest/interpreter/test-interpreter-intrinsics.cc
@@ -112,6 +112,27 @@
   CHECK_EQ(*factory->false_value(), *helper.Invoke(helper.NewObject("42")));
   CHECK_EQ(*factory->true_value(),
            *helper.Invoke(helper.NewObject("new Proxy({},{})")));
+}
+
+TEST(IsRegExp) {
+  HandleAndZoneScope handles;
+
+  InvokeIntrinsicHelper helper(handles.main_isolate(), handles.main_zone(),
+                               Runtime::kInlineIsRegExp);
+  Factory* factory = handles.main_isolate()->factory();
+
+  CHECK_EQ(*factory->false_value(),
+           *helper.Invoke(helper.NewObject("new Date()")));
+  CHECK_EQ(*factory->false_value(),
+           *helper.Invoke(helper.NewObject("(function() {})")));
+  CHECK_EQ(*factory->false_value(), *helper.Invoke(helper.NewObject("([1])")));
+  CHECK_EQ(*factory->false_value(), *helper.Invoke(helper.NewObject("({})")));
+  CHECK_EQ(*factory->true_value(), *helper.Invoke(helper.NewObject("(/x/)")));
+  CHECK_EQ(*factory->false_value(), *helper.Invoke(helper.Undefined()));
+  CHECK_EQ(*factory->false_value(), *helper.Invoke(helper.Null()));
+  CHECK_EQ(*factory->false_value(),
+           *helper.Invoke(helper.NewObject("'string'")));
+  CHECK_EQ(*factory->false_value(), *helper.Invoke(helper.NewObject("42")));
 }
 
 TEST(IsTypedArray) {