Make closures optimizable by Crankshaft compiler.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 34316319aa3ebc61db008d7e663e27b2461fe0ed..2e0f029b2fc796302838f08f39a782ca5742856e 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -106,6 +106,7 @@ class LChunkBuilder;
 //     HGlobalObject
 //     HGlobalReceiver
 //     HLeaveInlined
+//     HLoadContextSlot
 //     HLoadGlobal
 //     HMaterializedLiteral
 //       HArrayLiteral
@@ -213,6 +214,7 @@ class LChunkBuilder;
   V(HasCachedArrayIndex)                       \
   V(ClassOfTest)                               \
   V(LeaveInlined)                              \
+  V(LoadContextSlot)                           \
   V(LoadElements)                              \
   V(LoadGlobal)                                \
   V(LoadKeyedFastElement)                      \
@@ -2503,6 +2505,39 @@ class HStoreGlobal: public HUnaryOperation {
 };
 
 
+class HLoadContextSlot: public HInstruction {
+ public:
+  HLoadContextSlot(Handle<Context> context, int index)
+      : context_(context), index_(index) {
+    set_representation(Representation::Tagged());
+    SetFlag(kUseGVN);
+    SetFlag(kDependsOnCalls);
+  }
+
+  Handle<Context>  context() const { return context_; }
+  int index() const { return index_; }
+
+  virtual void PrintDataTo(StringStream* stream) const;
+
+  virtual intptr_t Hashcode() const {
+    ASSERT(!Heap::allow_allocation(false));
+    return reinterpret_cast<intptr_t>(*context_) * 7 + index_;
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(LoadContextSlot, "load_context_slot")
+
+ protected:
+  virtual bool DataEquals(HValue* other) const {
+    HLoadContextSlot* b = HLoadContextSlot::cast(other);
+    return context_.is_identical_to(b->context()) && index_ == b->index();
+  }
+
+ private:
+  Handle<Context> context_;
+  int index_;
+};
+
+
 class HLoadNamedField: public HUnaryOperation {
  public:
   HLoadNamedField(HValue* object, bool is_in_object, int offset)