blob_constructor_test is passing now.

pkg/dev_compiler/test/browser/language_tests.js

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 define(['dart_sdk', 'async_helper', 'expect', 'unittest', 'is', 'require'],
       function(dart_sdk, async_helper, expect, unittest, is, require) {
   'use strict';
 
   async_helper = async_helper.async_helper;
   let minitest = expect.minitest;
@@ skipping 407 matching lines @@
       'streamed_conversion_json_utf8_encode_test': skip_timeout,
       'streamed_conversion_utf8_decode_test': skip_timeout,
       'streamed_conversion_utf8_encode_test': skip_timeout,
       'utf85_test': skip_timeout,
     },
 
     'lib/html': {
       'async_spawnuri_test': async_unittest,
       'async_test': async_unittest,
       'audiocontext_test': is.chrome('<=54') ? fail : pass, // was sdk#27578, needs triage
-      'blob_constructor_test': 'fail', // was sdk#27578, needs triage
       'canvas_test': ['unittest'],
       'canvasrenderingcontext2d_test': ['unittest'],
       'cross_domain_iframe_test': async_unittest,
       'cssstyledeclaration_test': async_unittest,
       'css_test': async_unittest,
 
       // This is failing with a range error, I'm guessing because it's looking
       // for a stylesheet and the page has none.
       'css_rule_list_test': 'fail',
       'custom_element_method_clash_test': async_unittest,
@@ skipping 404 matching lines @@
 
     for (let action of unittest_tests) {
       try {
         action();
       } catch (e) {
         console.error("Caught error tying to setup test:", e);
       }
     }
   });
 });