Fix custom formatter setup

pkg/dev_compiler/lib/js/legacy/dart_library.js

Index: pkg/dev_compiler/lib/js/legacy/dart_library.js
diff --git a/pkg/dev_compiler/lib/js/legacy/dart_library.js b/pkg/dev_compiler/lib/js/legacy/dart_library.js
index bb6ab0298b4104863721541114dbef67b0b89a07..4901310d7dc19511a577280266e389a8e4c13afd 100644
--- a/pkg/dev_compiler/lib/js/legacy/dart_library.js
+++ b/pkg/dev_compiler/lib/js/legacy/dart_library.js
@@ -169,6 +169,10 @@ dart_library =
     let library = import_(moduleName)[libraryName];
     let dart_sdk = import_('dart_sdk');
 
+    // This import is only needed for chrome debugging. We should provide an
+    // option to compile without it.

[Jacob, 2017/03/09 02:59:07]

you should make sure registerDevtoolsFormatter isn't called multiple times.

+    dart_sdk._debugger.registerDevtoolsFormatter();
+
     if (!_currentIsolate) {
       // Create isolate.
       _currentIsolate = true;
@@ -183,10 +187,6 @@ dart_library =
   function bootstrap() {
     if (_bootstrapped) return;
     _bootstrapped = true;
-
-    // This import is only needed for chrome debugging. We should provide an
-    // option to compile without it.
-    dart_sdk._debugger.registerDevtoolsFormatter();

[vsm, 2017/03/09 02:54:07]

dart_sdk isn't defined here - breaking internal tests

   }
 
 })(dart_library);