Revert of [regexp] Remove IsRegExp intrinsic

src/full-codegen/arm64/full-codegen-arm64.cc

Index: src/full-codegen/arm64/full-codegen-arm64.cc
diff --git a/src/full-codegen/arm64/full-codegen-arm64.cc b/src/full-codegen/arm64/full-codegen-arm64.cc
index c73ccb6cce91f6152735f7de4726d13e610c66fa..84c6b21d714d6bbc6d1db46fa9ad62a64ccd6c89 100644
--- a/src/full-codegen/arm64/full-codegen-arm64.cc
+++ b/src/full-codegen/arm64/full-codegen-arm64.cc
@@ -1960,6 +1960,28 @@
 
   __ JumpIfSmi(x0, if_false);
   __ CompareObjectType(x0, x10, x11, JS_TYPED_ARRAY_TYPE);
+  PrepareForBailoutBeforeSplit(expr, true, if_true, if_false);
+  Split(eq, if_true, if_false, fall_through);
+
+  context()->Plug(if_true, if_false);
+}
+
+
+void FullCodeGenerator::EmitIsRegExp(CallRuntime* expr) {
+  ZoneList<Expression*>* args = expr->arguments();
+  DCHECK(args->length() == 1);
+
+  VisitForAccumulatorValue(args->at(0));
+
+  Label materialize_true, materialize_false;
+  Label* if_true = NULL;
+  Label* if_false = NULL;
+  Label* fall_through = NULL;
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
+
+  __ JumpIfSmi(x0, if_false);
+  __ CompareObjectType(x0, x10, x11, JS_REGEXP_TYPE);
   PrepareForBailoutBeforeSplit(expr, true, if_true, if_false);
   Split(eq, if_true, if_false, fall_through);