Revert of [regexp] Remove IsRegExp intrinsic

test/cctest/compiler/test-run-intrinsics.cc

Index: test/cctest/compiler/test-run-intrinsics.cc
diff --git a/test/cctest/compiler/test-run-intrinsics.cc b/test/cctest/compiler/test-run-intrinsics.cc
index 515e096f4474c09000064da856d2b9271c9a8e51..47116ad6743278006e943634f50a5822a24c161c 100644
--- a/test/cctest/compiler/test-run-intrinsics.cc
+++ b/test/cctest/compiler/test-run-intrinsics.cc
@@ -80,6 +80,21 @@
 }
 
 
+TEST(IsRegExp) {
+  FunctionTester T("(function(a) { return %_IsRegExp(a); })", flags);
+
+  T.CheckFalse(T.NewObject("new Date()"));
+  T.CheckFalse(T.NewObject("(function() {})"));
+  T.CheckFalse(T.NewObject("([1])"));
+  T.CheckFalse(T.NewObject("({})"));
+  T.CheckTrue(T.NewObject("(/x/)"));
+  T.CheckFalse(T.undefined());
+  T.CheckFalse(T.null());
+  T.CheckFalse(T.Val("x"));
+  T.CheckFalse(T.Val(1));
+}
+
+
 TEST(IsSmi) {
   FunctionTester T("(function(a) { return %_IsSmi(a); })", flags);