Deal with unhandled exceptions the same way in all Dart api functions.

runtime/vm/unit_test.h

 // Copyright (c) 2011, 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.
 
 #ifndef VM_UNIT_TEST_H_
 #define VM_UNIT_TEST_H_
 
 #include "include/dart_api.h"
 
 #include "vm/ast.h"
@@ skipping 234 matching lines @@
   // Test the Compiler::CompileScript functionality by checking the return
   // value to see if no parse errors were reported.
   static bool TestCompileScript(const Library& library, const Script& script);
 
   // Test the Compiler::CompileFunction functionality by checking the return
   // value to see if no parse errors were reported.
   static bool TestCompileFunction(const Function& function);
 };
 
 #define EXPECT_VALID(handle)                                                  \
-  if (!Dart_IsValid((handle))) {                                              \
+  if (Dart_IsError((handle))) {                                               \
     dart::Expect(__FILE__, __LINE__).Fail("invalid handle '%s':\n    '%s'\n", \
                                           #handle, Dart_GetError(handle));    \
   }
 
 }  // namespace dart
 
 #endif  // VM_UNIT_TEST_H_