Remove signature classes from the VM.

runtime/vm/raw_object.cc

Index: runtime/vm/raw_object.cc
diff --git a/runtime/vm/raw_object.cc b/runtime/vm/raw_object.cc
index ba53d37e4761b6fd03ec9b4e167dbda8a08a5dfd..730d50a04f0a37cac44440c18493bbaddaa339d1 100644
--- a/runtime/vm/raw_object.cc
+++ b/runtime/vm/raw_object.cc
@@ -336,6 +336,13 @@ intptr_t RawType::VisitTypePointers(
 }
 
 
+intptr_t RawFunctionType::VisitFunctionTypePointers(
+    RawFunctionType* raw_obj, ObjectPointerVisitor* visitor) {
+  visitor->VisitPointers(raw_obj->from(), raw_obj->to());
+  return FunctionType::InstanceSize();
+}
+
+
 intptr_t RawTypeRef::VisitTypeRefPointers(
     RawTypeRef* raw_obj, ObjectPointerVisitor* visitor) {
   visitor->VisitPointers(raw_obj->from(), raw_obj->to());
@@ -379,6 +386,13 @@ intptr_t RawPatchClass::VisitPatchClassPointers(RawPatchClass* raw_obj,
 }
 
 
+intptr_t RawClosure::VisitClosurePointers(
+    RawClosure* raw_obj, ObjectPointerVisitor* visitor) {
+  visitor->VisitPointers(raw_obj->from(), raw_obj->to());
+  return Closure::InstanceSize();
+}
+
+
 intptr_t RawClosureData::VisitClosureDataPointers(
     RawClosureData* raw_obj, ObjectPointerVisitor* visitor) {
   visitor->VisitPointers(raw_obj->from(), raw_obj->to());