Create a internal, global native context used only for generated code stubs

src/code-stubs.js

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+(function(global, code_stubs) {
+
+
+code_stubs.StringLengthTFStub = function StringLengthTFStub(call_conv,
+                                                            minor_key) {
+  var stub = function(receiver, name, i, v) {
+    // i and v are dummy parameters mandated by the InterfaceDescriptor,
+    // (LoadWithVectorDescriptor).
+    return %_StringGetLength(%_JSValueGetValue(receiver));
+  }
+  return stub;
+}
+
+
+code_stubs.StringAddTFStub = function StringAddTFStub(call_conv, minor_key) {
+  var stub = function(left, right) {
+    return %StringAdd(left, right);
+  }
+  return stub;
+}
+
+
+code_stubs.MathFloorStub = function MathFloorStub(call_conv, minor_key) {
+  var stub = function(f, i, v) {
+    // |f| is calling function's JSFunction
+    // |i| is TypeFeedbackVector slot # of callee's CallIC for Math.floor call
+    // |v| is the value to floor
+    var r = %_MathFloor(+v);
+    if (%_IsMinusZero(r)) {
+      // Collect type feedback when the result of the floor is -0. This is
+      // accomplished by storing a sentinel in the second, "extra"
+      // TypeFeedbackVector slot corresponding to the Math.floor CallIC call in
+      // the caller's TypeVector.
+      %_FixedArraySet(%_GetTypeFeedbackVector(f), ((i|0)+1)|0, 1);
+      return -0;
+    }
+    // Return integers in smi range as smis.
+    var trunc = r|0;
+    if (trunc === r) {
+      return trunc;
+    }
+    return r;
+  }
+  return stub;
+}
+
+})