Revert of [regexp] Remove IsRegExp intrinsic

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

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compilation-info.h"
 #include "test/cctest/compiler/function-tester.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
@@ skipping 62 matching lines @@
   T.CheckFalse(T.NewObject("([1])"));
   T.CheckFalse(T.NewObject("({})"));
   T.CheckFalse(T.NewObject("(/x/)"));
   T.CheckFalse(T.undefined());
   T.CheckFalse(T.null());
   T.CheckFalse(T.Val("x"));
   T.CheckFalse(T.Val(1));
 }
 
 
+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);
 
   T.CheckFalse(T.NewObject("new Date()"));
   T.CheckFalse(T.NewObject("(function() {})"));
   T.CheckFalse(T.NewObject("([1])"));
   T.CheckFalse(T.NewObject("({})"));
   T.CheckFalse(T.NewObject("(/x/)"));
   T.CheckFalse(T.undefined());
   T.CheckTrue(T.Val(1));
@@ skipping 36 matching lines @@
   FunctionTester T("(function(a,b) { return %_SubString(a,b,b+3); })", flags);
 
   T.CheckCall(T.Val("aaa"), T.Val("aaabbb"), T.Val(0.0));
   T.CheckCall(T.Val("abb"), T.Val("aaabbb"), T.Val(2));
   T.CheckCall(T.Val("aaa"), T.Val("aaa"), T.Val(0.0));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8