Expose APIs for detecting boxed primitives, native errors and Math.

src/factory.h

Index: src/factory.h
diff --git a/src/factory.h b/src/factory.h
index 19f09a15ce3ddae09ed05b06cf49a98b39f2f377..36f46f587dcb8fd773c2c6ba08345c53267853fb 100644
--- a/src/factory.h
+++ b/src/factory.h
@@ -225,6 +225,10 @@ class Factory {
   Handle<Object> NewNumberFromInt(int value);
   Handle<Object> NewNumberFromUint(uint32_t value);
 
+  Handle<Object> NewBoxedNumber(double value);
+  Handle<Object> NewBoxedString(Handle<String> value);
+  Handle<Object> NewBoxedBoolean(bool value);
+
   // These objects are used by the api to create env-independent data
   // structures in the heap.
   Handle<JSObject> NewNeanderObject();