Don't read platform files during testing, and avoid trimming broken programs.

pkg/front_end/test/fasta/compile.status

Index: pkg/front_end/test/fasta/compile.status
diff --git a/pkg/front_end/test/fasta/compile.status b/pkg/front_end/test/fasta/compile.status
index f5a29a2abe1495e99ad270e50bf4ba34a748cd1d..8c3c88dc042b981b58b3dfe9edd95ca6b6d62537 100644
--- a/pkg/front_end/test/fasta/compile.status
+++ b/pkg/front_end/test/fasta/compile.status
@@ -2,6 +2,8 @@
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE.md file.
 
+rasta/unsupported_platform_library: RuntimeError # OK, this must report an error at runtime.
+
 # Status file for the compile_test.dart (notice c, not k) test suite. This is
 # testing generating Kernel ASTs directly, that is, code in
 # pkg/fasta/lib/src/kernel/.
@@ -355,4 +357,3 @@ rasta/unresolved: Fail
 rasta/unresolved_constructor: Fail
 rasta/unresolved_for_in: Fail
 rasta/unresolved_recovery: Fail
-rasta/unsupported_platform_library: Fail