Add token index position to classes and types for more accurate error reporting.

runtime/vm/dart_api_impl_test.cc

Index: runtime/vm/dart_api_impl_test.cc
===================================================================
--- runtime/vm/dart_api_impl_test.cc	(revision 3925)
+++ runtime/vm/dart_api_impl_test.cc	(working copy)
@@ -1495,10 +1495,8 @@
   // We expect the test script to fail finalization with the error below:
   EXPECT(Dart_IsError(result));
   Dart_Handle expected_error = Dart_Error(
-      "'dart:test-lib': Error: class 'NativeFields' is trying to extend a "
-      "native fields class, but library '%s' has no native resolvers",
-      TestCase::url());
-  EXPECT_STREQ(Dart_GetError(expected_error), Dart_GetError(result));
+      "'dart:test-lib': Error: line 1 pos 38: class 'NativeFields' is trying");

[siva, 2012/02/06 18:13:08]

Why did you chop of the rest of the error regarding library not having native
resolvers. I think that is a useful test which validates we are not finding
native resolvers.

[regis, 2012/02/06 19:43:16]

The emitted error message is now much longer, since it contains the exact
position as well as a snippet of the faulty code. I think that verifying only a
prefix of the error message is sufficient. Otherwise, I would have to copy
multiple lines of output in this test. I can make the prefix longer if you think
it is not testing enough in its current form.

[regis, 2012/02/06 20:07:48]

As discussed, I will not chop off the error message so short  as to test the
library url. I'll send you a cl.

+  EXPECT_SUBSTRING(Dart_GetError(expected_error), Dart_GetError(result));
 }