pkg/docgen: support better const rendering of String, List, and empty Map

pkg/pkg.status

Index: pkg/pkg.status
diff --git a/pkg/pkg.status b/pkg/pkg.status
index 66d6014490cc8991840d27d99ee21460315416cc..e6531f5c1180cb2dce84180d63298ed3b6c95646 100644
--- a/pkg/pkg.status
+++ b/pkg/pkg.status
@@ -17,39 +17,29 @@ polymer/example/scoped_style/*: Skip
 scheduled_test/test/scheduled_server_test: Pass, Fail # 13524
 scheduled_test/test/scheduled_process_test: Pass, Slow # Issue 9231
 
-[ $compiler == dart2js && $mode == debug ]
-docgen/test/generate_json_test: Skip # Way too slow
-docgen/test/multi_library_test: Skip # Way too slow
-docgen/test/single_library_test: Skip # Way too slow
-docgen/test/typedef_test: Skip # Way too slow
-
 [ $runtime == vm && $mode == debug]
-docgen/test/only_lib_content_in_pkg_test: Skip # Slow
-polymer/test/build/all_phases_test: Skip # Slow
 analysis_server/test/analysis_server_test: Pass, Timeout
 analysis_server/test/domain_context_test: Pass, Timeout
 analysis_server/test/domain_server_test: Pass, Timeout
 analyzer/test/generated/element_test: Pass, Timeout
 analyzer/test/generated/parser_test: Pass, Timeout
 code_transformers/test/resolver_test: Pass, Timeout
-docgen/test/only_lib_content_in_pkg_test: Pass, Timeout
-polymer_expressions/test/globals_test: Pass, Timeout
-polymer/test/build/all_phases_test: Pass, Timeout
+docgen/test/*: Skip # Slow
+polymer/test/build/all_phases_test: Skip # Slow
 polymer/test/build/script_compactor_test: Pass, Timeout
+polymer_expressions/test/globals_test: Pass, Timeout
 smoke/test/codegen/end_to_end_test: Pass, Timeout
 smoke/test/codegen/recorder_test: Pass, Timeout
 template_binding/test/template_binding_test: Pass, Timeout
 third_party/html5lib/test/tokenizer_test: Pass, Timeout
 
 [ $runtime == vm && ( $arch == simarm || $arch == simmips ) ]
-docgen/test/only_lib_content_in_pkg_test: Skip # slow
-docgen/test/typedef_test: Skip # slow
 barback/test/too_many_open_files_test: Skip # 14220
-third_party/html5lib/test/tokenizer_test: Pass, Slow
-docgen/test/generate_json_test: Skip # Issue 17003
-polymer/test/build/script_compactor_test: Skip # Slow
-polymer/test/build/all_phases_test: Skip # Slow
 code_transformers/test/resolver_test: Skip # Issue 17908
+docgen/test/*: Skip # Issue 17003
+polymer/test/build/all_phases_test: Skip # Slow
+polymer/test/build/script_compactor_test: Skip # Slow
+third_party/html5lib/test/tokenizer_test: Pass, Slow
 
 [ $compiler == dart2js ]
 collection/test/equality_test/01: Fail # Issue 1533
@@ -58,7 +48,7 @@ collection/test/equality_test/03: Fail # Issue 1533
 collection/test/equality_test/04: Fail # Issue 1533
 collection/test/equality_test/05: Fail # Issue 1533
 collection/test/equality_test/none: Pass, Fail # Issue 14348
-docgen/test/multi_library_test: Slow, Pass # issue 17060
+docgen/test/*: Skip # Far too slow
 third_party/angular_tests/browser_test: Pass, Slow # Large dart2js compile time
 typed_data/test/typed_buffers_test/01: Fail # Not supporting Int64List, Uint64List.
 
@@ -72,7 +62,6 @@ serialization/test/serialization_test: Skip
 
 [ $runtime == jsshell ]
 analyzer/test/generated/element_test: Pass, Slow # Issue 16473
-docgen/test/typedef_test: Slow, Pass # issue 17060
 
 [ $runtime == d8 || $runtime == jsshell ]
 stack_trace/test/chain_test: Fail # Issues 15171 and 15105
@@ -199,7 +188,6 @@ polymer/example/component: Fail # Issue 13198
 polymer/test/mirror_loader_test: Skip # tests development only behavior
 
 [ $compiler == dart2js && $runtime == chromeOnAndroid ]
-docgen/test/single_library_test: Fail # TODO(kasperl): Please triage.
 intl/test/date_time_format_http_request_test: Fail # TODO(kasperl): Please triage.
 
 [ $browser ]