[runtime] Introduce FastNewStrictArgumentsStub to optimize strict arguments.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index ebe4762d3b2580cc57a20ae34174b13b8bbca941..35e750c013d4107ce812bdc30615530febb5130d 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -2606,7 +2606,7 @@ class JSDataPropertyDescriptor: public JSObject {
 
 
 // JSIteratorResult is just a JSObject with a specific initial map.
-// This initial map adds in-object properties for "done" and "value,
+// This initial map adds in-object properties for "done" and "value",
 // as specified by ES6 section 25.1.1.3 The IteratorResult Interface
 class JSIteratorResult: public JSObject {
  public:
@@ -2623,6 +2623,47 @@ class JSIteratorResult: public JSObject {
 };
 
 
+// Common superclass for JSSloppyArgumentsObject and JSStrictArgumentsObject.
+class JSArgumentsObject: public JSObject {
+ public:
+  // Offsets of object fields.
+  static const int kLengthOffset = JSObject::kHeaderSize;
+  static const int kHeaderSize = kLengthOffset + kPointerSize;
+  // Indices of in-object properties.
+  static const int kLengthIndex = 0;
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(JSArgumentsObject);
+};
+
+
+// JSSloppyArgumentsObject is just a JSObject with specific initial map.
+// This initial map adds in-object properties for "length" and "callee".
+class JSSloppyArgumentsObject: public JSArgumentsObject {
+ public:
+  // Offsets of object fields.
+  static const int kCalleeOffset = JSArgumentsObject::kHeaderSize;
+  static const int kSize = kCalleeOffset + kPointerSize;
+  // Indices of in-object properties.
+  static const int kCalleeIndex = 1;
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(JSSloppyArgumentsObject);
+};
+
+
+// JSStrictArgumentsObject is just a JSObject with specific initial map.
+// This initial map adds an in-object property for "length".
+class JSStrictArgumentsObject: public JSArgumentsObject {
+ public:
+  // Offsets of object fields.
+  static const int kSize = JSArgumentsObject::kHeaderSize;
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(JSStrictArgumentsObject);
+};
+
+
 // Common superclass for FixedArrays that allow implementations to share
 // common accessors and some code paths.
 class FixedArrayBase: public HeapObject {