Ship dart2js output for dev_compiler/web in the sdk.

sdk/BUILD.gn

 # Copyright (c) 2017, 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.
 
 # The SDK for Fuchsia does not include:
 #  dart2js
 #  dartdoc
 #  ddc
 # and libraries that are browser-specific, since these are not used and require
 # significant time to build.
@@ skipping 369 matching lines @@
     ]
 
     script = "../tools/create_sdk.py"
     args = [
       "--sdk_output_dir",
       rebase_path("$root_out_dir/dart-sdk"),
       "--snapshot_location",
       rebase_path("$root_gen_dir"),
     ]
   }
+
+  copy("copy_dev_compiler_tools") {
+    deps = [
+      ":create_sdk",
+      "../utils/dartdevc:dartdevc_web",
+      "../utils/dartdevc:stack_trace_mapper",
+    ]
+    dart_out = get_label_info("../utils/dartdevc:dartdevc_web", "root_out_dir")
+    sources = [
+      "$dart_out/dev_compiler/build/web/ddc_web_compiler.js",
+      "$dart_out/dev_compiler/build/web/dart_stack_trace_mapper.js",
+    ]
+    outputs = [
+      "$root_out_dir/dart-sdk/lib/dev_compiler/web/{{source_file_part}}",
+    ]
+  }
 }