Fix equality of implicit closures in the Dart VM.

runtime/lib/function.cc

Index: runtime/lib/function.cc
===================================================================
--- runtime/lib/function.cc	(revision 25920)
+++ runtime/lib/function.cc	(working copy)
@@ -27,4 +27,35 @@
   return result.raw();
 }
 
+
+DEFINE_NATIVE_ENTRY(Closure_comparison, 2) {
+  GET_NATIVE_ARGUMENT(Instance, a, arguments->NativeArgAt(0));
+  GET_NATIVE_ARGUMENT(Instance, b, arguments->NativeArgAt(1));
+  if (a.raw() == b.raw()) return Bool::True().raw();
+  if (a.IsClosure() && b.IsClosure()) {
+    const Function& func_a = Function::Handle(Closure::function(a));
+    const Function& func_b = Function::Handle(Closure::function(b));
+    if (func_a.raw() == func_b.raw()) {
+      const Context& context_a = Context::Handle(Closure::context(a));
+      const Context& context_b = Context::Handle(Closure::context(b));
+      const Instance& receiver_a = Instance::Handle(context_a.At(0));
+      const Instance& receiver_b = Instance::Handle(context_b.At(0));
+      if (receiver_a.raw() == receiver_b.raw()) return Bool::True().raw();
+    }
+  }
+  return Bool::False().raw();
+}
+
+
+DEFINE_NATIVE_ENTRY(Closure_hashCode, 1) {
+  GET_NATIVE_ARGUMENT(Instance, a, arguments->NativeArgAt(0));
+  if (a.IsClosure()) {
+    const Function& func = Function::Handle(Closure::function(a));
+    intptr_t result = String::Handle(func.name()).Hash();
+    // TODO(fschneider): Also use receiver for hash.
+    return Smi::New(result);
+  }
+  return Object::null();
+}
+
 }  // namespace dart