Infra for running lib tests

This is in prep for #441

[email protected]

Review URL: https://codereview.chromium.org/1673863002 .

Author: vsmenon

pkg/dev_compiler/.gitignore

@@ -17,6 +17,7 @@ doc/api/
 # Ignore test output
 test/codegen/expect/dev_compiler/
 test/codegen/expect/language/
+test/codegen/expect/lib/
 test/codegen/expect/sunflower/dev_compiler/
 test/codegen/expect/matcher/
 test/codegen/language/*_multi.dart

pkg/dev_compiler/karma.conf.js

@@ -30,6 +30,7 @@ module.exports = function(config) {
       'test/codegen/expect/language-all.js',
       'test/codegen/expect/language/sub/sub.js',
       'test/codegen/expect/language/*.lib',
+      'test/codegen/expect/lib-typed_data-all.js',
       'test/browser/*.js',
       'test-main.js',
     ],