Fraction class prototype and test (not to be committed).

runtime/vm/dart_entry.cc

Index: runtime/vm/dart_entry.cc
diff --git a/runtime/vm/dart_entry.cc b/runtime/vm/dart_entry.cc
index c9e7769fba4a0b47400b6ee8dfcaf4302c9ab65f..e2327fff9f610e3d6b37b49bd8177d1d88fe9c84 100644
--- a/runtime/vm/dart_entry.cc
+++ b/runtime/vm/dart_entry.cc
@@ -425,15 +425,22 @@ void ArgumentsDescriptor::InitOnce() {
 RawObject* DartLibraryCalls::InstanceCreate(const Library& lib,
                                             const String& class_name,
                                             const String& constructor_name,
+                                            bool factory,
                                             const Array& arguments) {
   const Class& cls = Class::Handle(lib.LookupClassAllowPrivate(class_name));
+  // Class may not be finalized yet, but will be as the constructor is compiled.
   ASSERT(!cls.IsNull());
   // For now, we only support a non-parameterized or raw type.
-  const int kNumExtraArgs = 1;  // implicit rcvr arg.
-  const Instance& exception_object = Instance::Handle(Instance::New(cls));
+  const int kNumExtraArgs = 1;  // Implicit rcvr arg or empty factory type args.
+  Instance& exception_object = Instance::Handle();
   const Array& constructor_arguments =
     Array::Handle(Array::New(arguments.Length() + kNumExtraArgs));
-  constructor_arguments.SetAt(0, exception_object);
+  if (factory) {
+    constructor_arguments.SetAt(0, TypeArguments::Handle());
+  } else {
+    exception_object = Instance::New(cls);
+    constructor_arguments.SetAt(0, exception_object);
+  }
   Object& obj = Object::Handle();
   for (intptr_t i = 0; i < arguments.Length(); i++) {
     obj = arguments.At(i);
@@ -443,13 +450,14 @@ RawObject* DartLibraryCalls::InstanceCreate(const Library& lib,
   const String& function_name = String::Handle(
       String::Concat(class_name, constructor_name));
   const Function& constructor =
-      Function::Handle(cls.LookupConstructorAllowPrivate(function_name));
+      Function::Handle(factory ?
+                       cls.LookupFactoryAllowPrivate(function_name) :
+                       cls.LookupConstructorAllowPrivate(function_name));
   ASSERT(!constructor.IsNull());
   const Object& retval =
     Object::Handle(DartEntry::InvokeFunction(constructor,
                                              constructor_arguments));
-  ASSERT(retval.IsNull() || retval.IsError());
-  if (retval.IsError()) {
+  if (factory || retval.IsError()) {
     return retval.raw();
   }
   return exception_object.raw();