Expose remaining 'errors' in an unified dart:core.

runtime/vm/exceptions.cc

Index: runtime/vm/exceptions.cc
diff --git a/runtime/vm/exceptions.cc b/runtime/vm/exceptions.cc
index 7242b1fb07c561f860fc628b03e0978ffccfe451..e42d463c49f19ec889b570b4ab83a4d11dc5c5bb 100644
--- a/runtime/vm/exceptions.cc
+++ b/runtime/vm/exceptions.cc
@@ -260,11 +260,11 @@ void Exceptions::CreateAndThrowTypeError(intptr_t location,
   Instance& type_error = Instance::Handle();
   Class& cls = Class::Handle();
   if (dst_name.Equals(kCastExceptionDstName)) {
-    type_error = NewInstance("CastException");
+    type_error = NewInstance("CastExceptionImplementation");
     cls = type_error.clazz();
     cls = cls.SuperClass();
   } else {
-    type_error = NewInstance("TypeError");
+    type_error = NewInstance("TypeErrorImplementation");
     cls = type_error.clazz();
   }