Inline Array.shift() fast path instead of using a code stub.

src/code-stubs.h

Index: src/code-stubs.h
diff --git a/src/code-stubs.h b/src/code-stubs.h
index c7fc94496307a45e8e12e87109597fafd03d208e..cb0edc698b026d48921450026ade5c69dd6b21f6 100644
--- a/src/code-stubs.h
+++ b/src/code-stubs.h
@@ -16,7 +16,6 @@ namespace internal {
 
 // List of code stubs used on all platforms.
 #define CODE_STUB_LIST_ALL_PLATFORMS(V)  \
-  V(ArrayShift)                          \
   V(CallFunction)                        \
   V(CallConstruct)                       \
   V(BinaryOpIC)                          \
@@ -2412,36 +2411,6 @@ class ElementsTransitionAndStoreStub : public HydrogenCodeStub {
 };
 
 
-class ArrayShiftStub V8_FINAL : public HydrogenCodeStub {
- public:
-  ArrayShiftStub(Isolate* isolate, ElementsKind kind)
-      : HydrogenCodeStub(isolate), kind_(kind) { }
-
-  ElementsKind kind() const { return kind_; }
-
-  virtual Handle<Code> GenerateCode() V8_OVERRIDE;
-
-  virtual void InitializeInterfaceDescriptor(
-      CodeStubInterfaceDescriptor* descriptor) V8_OVERRIDE;
-
-  // Inline Array.shift() for arrays up to this length.
-  static const int kInlineThreshold = 16;
-
-  // Parameters accessed via CodeStubGraphBuilder::GetParameter()
-  static const int kReceiver = 0;
-
- private:
-  Major MajorKey() { return ArrayShift; }
-  int NotMissMinorKey() {
-    return kind_;
-  }
-
-  ElementsKind kind_;
-
-  DISALLOW_COPY_AND_ASSIGN(ArrayShiftStub);
-};
-
-
 class StoreArrayLiteralElementStub : public PlatformCodeStub {
  public:
   explicit StoreArrayLiteralElementStub(Isolate* isolate)