Version 3.3.2....

src/x64/lithium-x64.h

Index: src/x64/lithium-x64.h
===================================================================
--- src/x64/lithium-x64.h	(revision 7683)
+++ src/x64/lithium-x64.h	(working copy)
@@ -102,6 +102,7 @@
   V(HasCachedArrayIndexAndBranch)               \
   V(HasInstanceType)                            \
   V(HasInstanceTypeAndBranch)                   \
+  V(In)                                         \
   V(InstanceOf)                                 \
   V(InstanceOfAndBranch)                        \
   V(InstanceOfKnownGlobal)                      \
@@ -830,6 +831,20 @@
 };
 
 
+class LIn: public LTemplateInstruction<1, 2, 0> {
+ public:
+  LIn(LOperand* key, LOperand* object) {
+    inputs_[0] = key;
+    inputs_[1] = object;
+  }
+
+  LOperand* key() { return inputs_[0]; }
+  LOperand* object() { return inputs_[1]; }
+
+  DECLARE_CONCRETE_INSTRUCTION(In, "in")
+};
+
+
 class LInstanceOf: public LTemplateInstruction<1, 2, 0> {
  public:
   LInstanceOf(LOperand* left, LOperand* right) {