Add implementations of the front end FileSystem API.

pkg/pkg.status

Index: pkg/pkg.status
diff --git a/pkg/pkg.status b/pkg/pkg.status
index d0913e69f4ab29f85d26be053a86d3ef9e6ce8a0..7e8afd042ac0830e5a76e1d64f09ce076dae3916 100644
--- a/pkg/pkg.status
+++ b/pkg/pkg.status
@@ -53,6 +53,8 @@ compiler/tool/*: SkipByDesign # Only meant to run on vm
 front_end/tool/*: SkipByDesign # Only meant to run on vm
 lookup_map/test/version_check_test: SkipByDesign # Only meant to run in vm.
 typed_data/test/typed_buffers_test/01: Fail # Not supporting Int64List, Uint64List.
+front_end/test/memory_file_system_test: CompileTimeError # Issue 23773

[Siggi Cherem (dart-lang), 2016/11/03 00:46:50]

This seems fine, we don't need to have it running in dart2js at this time. We
can revisit this if we have a valid use case for it in the future (e.g. if,
before having kernel working, we integrate FE with ddc and want to run it in the
browser to enable their debugging tools).

[Paul Berry, 2016/11/03 15:16:41]

Acknowledged.

+front_end/test/physical_file_system_test: CompileTimeError # Issue 23773

[Siggi Cherem (dart-lang), 2016/11/03 00:46:50]

this one should probably be skipByDesign since it's using dart:io

[Paul Berry, 2016/11/03 15:16:41]

Done.

 
 [ $compiler == dart2js && $builder_tag != dart2js_analyzer ]
 analyzer/test/*: Skip # Issue 26813