Revert of [regexp] Remove IsRegExp intrinsic

test/unittests/compiler/js-intrinsic-lowering-unittest.cc

Index: test/unittests/compiler/js-intrinsic-lowering-unittest.cc
diff --git a/test/unittests/compiler/js-intrinsic-lowering-unittest.cc b/test/unittests/compiler/js-intrinsic-lowering-unittest.cc
index e8bbc335783c6e3a2b5cdabe76685aee6c6999f9..780bf65df31c44d1912a80a75607dbb48a88200f 100644
--- a/test/unittests/compiler/js-intrinsic-lowering-unittest.cc
+++ b/test/unittests/compiler/js-intrinsic-lowering-unittest.cc
@@ -129,6 +129,37 @@
 
 
 // -----------------------------------------------------------------------------
+// %_IsRegExp
+
+
+TEST_F(JSIntrinsicLoweringTest, InlineIsRegExp) {
+  Node* const input = Parameter(0);
+  Node* const context = Parameter(1);
+  Node* const effect = graph()->start();
+  Node* const control = graph()->start();
+  Reduction const r = Reduce(
+      graph()->NewNode(javascript()->CallRuntime(Runtime::kInlineIsRegExp, 1),
+                       input, context, effect, control));
+  ASSERT_TRUE(r.Changed());
+
+  Node* phi = r.replacement();
+  Capture<Node*> branch, if_false;
+  EXPECT_THAT(
+      phi,
+      IsPhi(
+          MachineRepresentation::kTagged, IsFalseConstant(),
+          IsNumberEqual(IsLoadField(AccessBuilder::ForMapInstanceType(),
+                                    IsLoadField(AccessBuilder::ForMap(), input,
+                                                effect, CaptureEq(&if_false)),
+                                    effect, _),
+                        IsNumberConstant(JS_REGEXP_TYPE)),
+          IsMerge(IsIfTrue(AllOf(CaptureEq(&branch),
+                                 IsBranch(IsObjectIsSmi(input), control))),
+                  AllOf(CaptureEq(&if_false), IsIfFalse(CaptureEq(&branch))))));
+}
+
+
+// -----------------------------------------------------------------------------
 // %_IsJSReceiver