Introduce remote objects in Debugger protocol

runtime/vm/class_table.h

Index: runtime/vm/class_table.h
===================================================================
--- runtime/vm/class_table.h	(revision 7863)
+++ runtime/vm/class_table.h	(working copy)
@@ -20,11 +20,14 @@
   ~ClassTable();
 
   RawClass* At(intptr_t index) const {
-    ASSERT(index > 0);
-    ASSERT(index < top_);
+    ASSERT(IsValidIndex(index));
     return table_[index];
   }
 
+  intptr_t IsValidIndex(intptr_t index) const {
+    return (index > 0) && (index < top_);
+  }
+
   void Register(const Class& cls);
 
   void VisitObjectPointers(ObjectPointerVisitor* visitor);