Avoid constructing types with errors.

BUG=27626735

Rationale:
Do not construct classes with a link error. Without this,
the error type thought it was Object (mirror's method
IsObjectClass() returns true if there is no superclass).

Change-Id: I55ca8cc8cfc042210edf748aab10da4c6e345980
diff --git a/compiler/optimizing/nodes.cc b/compiler/optimizing/nodes.cc
index 1afa36a..af5ef04 100644
--- a/compiler/optimizing/nodes.cc
+++ b/compiler/optimizing/nodes.cc
@@ -2190,6 +2190,7 @@
   if (kIsDebugBuild) {
     ScopedObjectAccess soa(Thread::Current());
     DCHECK(IsValidHandle(type_handle));
+    DCHECK(!type_handle->IsErroneous());
     if (!is_exact) {
       DCHECK(!type_handle->CannotBeAssignedFromOtherTypes())
           << "Callers of ReferenceTypeInfo::Create should ensure is_exact is properly computed";