Fix a crash in compiler.

runtime/vm/intermediate_language.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/intermediate_language.h"
 
 #include "vm/bit_vector.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_allocator.h"
 #include "vm/flow_graph_builder.h"
@@ skipping 346 matching lines @@
   // We cannot give an answer if the given type is malformed.
   if (type.IsMalformed()) {
     return false;
   }
 
   // We should never test for an instance of null.
   ASSERT(!type.IsNullType());
 
   // Consider the compile type of the value.
   const AbstractType& compile_type = AbstractType::Handle(CompileType());
-  ASSERT(!compile_type.IsMalformed());
+  if (compile_type.IsMalformed()) {
+    return false;
+  }
 
   // If the compile type of the value is void, we are type checking the result
   // of a void function, which was checked to be null at the return statement
   // inside the function.
   if (compile_type.IsVoidType()) {
     ASSERT(FLAG_enable_type_checks);
     *is_instance = true;
     return true;
   }
 
@@ skipping 1706 matching lines @@
     new_max = new_max.Clamp();
   }
 
   return Range::Update(&range_, new_min, new_max);
 }
 
 
 #undef __
 
 }  // namespace dart