Use Copy-on-write arrays for cached regexp results.

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index a5ccaf509ca49a317df21b349987b08f479f6056..470b5bf72e66da68ab7b4f7a383ec5d37378ffd7 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -2628,6 +2628,14 @@ void FullCodeGenerator::EmitRegExpConstructResult(ZoneList<Expression*>* args) {
 }
 
 
+void FullCodeGenerator::EmitRegExpCloneResult(ZoneList<Expression*>* args) {
+  ASSERT(args->length() == 1);
+  VisitForValue(args->at(0), kStack);
+  __ CallRuntime(Runtime::kRegExpCloneResult, 1);
+  Apply(context_, rax);
+}
+
+
 void FullCodeGenerator::EmitSwapElements(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 3);
   VisitForValue(args->at(0), kStack);