Remove signature classes from the VM.

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
diff --git a/runtime/vm/dart_api_impl.cc b/runtime/vm/dart_api_impl.cc
index 040f302473750a83b71330764fd9cd1d3306bf79..d316138f93480972c01f8e758d06017b63ab859e 100644
--- a/runtime/vm/dart_api_impl.cc
+++ b/runtime/vm/dart_api_impl.cc
@@ -107,7 +107,7 @@ class FunctionVisitor : public ObjectVisitor {
       // Verify that the result type of a function is canonical or a
       // TypeParameter.
       typeHandle_ ^= funcHandle_.result_type();
-      ASSERT(typeHandle_.IsNull() ||
+      ASSERT(typeHandle_.IsMalformed() ||
              !typeHandle_.IsResolved() ||
              typeHandle_.IsTypeParameter() ||
              typeHandle_.IsCanonical());
@@ -116,8 +116,9 @@ class FunctionVisitor : public ObjectVisitor {
       const intptr_t num_parameters = funcHandle_.NumParameters();
       for (intptr_t i = 0; i < num_parameters; i++) {
         typeHandle_ = funcHandle_.ParameterTypeAt(i);
-        ASSERT(typeHandle_.IsTypeParameter() ||
+        ASSERT(typeHandle_.IsMalformed() ||
                !typeHandle_.IsResolved() ||
+               typeHandle_.IsTypeParameter() ||
                typeHandle_.IsCanonical());
       }
     }
@@ -1854,14 +1855,7 @@ DART_EXPORT bool Dart_IsTypeVariable(Dart_Handle handle) {
 
 
 DART_EXPORT bool Dart_IsClosure(Dart_Handle object) {
-  // We can't use a fast class index check here because there are many
-  // different signature classes for closures.
-  Thread* thread = Thread::Current();
-  CHECK_ISOLATE(thread->isolate());
-  ReusableObjectHandleScope reused_obj_handle(thread);
-  const Instance& closure_obj =
-      Api::UnwrapInstanceHandle(reused_obj_handle, object);
-  return (!closure_obj.IsNull() && closure_obj.IsClosure());
+  return Api::ClassId(object) == kClosureCid;
 }
 
 
@@ -1913,7 +1907,8 @@ DART_EXPORT Dart_Handle Dart_InstanceGetType(Dart_Handle instance) {
   if (!obj.IsInstance()) {
     RETURN_TYPE_ERROR(Z, instance, Instance);
   }
-  const Type& type = Type::Handle(Instance::Cast(obj).GetType());
+  const AbstractType& type =
+      AbstractType::Handle(Instance::Cast(obj).GetType());
   return Api::NewHandle(T, type.Canonicalize());
 }
 
@@ -3884,7 +3879,7 @@ DART_EXPORT Dart_Handle Dart_InvokeConstructor(Dart_Handle object,
 
   // Construct name of the constructor to invoke.
   const String& constructor_name = Api::UnwrapStringHandle(Z, name);
-  const Type& type_obj = Type::Handle(Z, instance.GetType());
+  const AbstractType& type_obj = AbstractType::Handle(Z, instance.GetType());
   const Class& cls = Class::Handle(Z, type_obj.type_class());
   const String& class_name = String::Handle(Z, cls.Name());
   const Array& strings = Array::Handle(Z, Array::New(3));