First pass at asynchronous input loading in dart2js.

tests/compiler/dart2js/message_kind_helper.dart

Index: tests/compiler/dart2js/message_kind_helper.dart
diff --git a/tests/compiler/dart2js/message_kind_helper.dart b/tests/compiler/dart2js/message_kind_helper.dart
index 6302bf190608302f6e25b8b008093c02377840c4..3ae68c3cc56f51b61aa0effd746431b3deafa8b2 100644
--- a/tests/compiler/dart2js/message_kind_helper.dart
+++ b/tests/compiler/dart2js/message_kind_helper.dart
@@ -5,6 +5,7 @@
 library dart2js.test.message_kind_helper;
 
 import 'package:expect/expect.dart';
+import 'dart:async';
 
 import '../../../sdk/lib/_internal/compiler/implementation/dart2jslib.dart' show
     Compiler,
@@ -14,8 +15,8 @@ import 'memory_compiler.dart';
 
 const String ESCAPE_REGEXP = r'[[\]{}()*+?.\\^$|]';
 
-Compiler check(MessageKind kind, Compiler cachedCompiler,
-               {bool expectNoHowToFix: false}) {
+Future<Compiler> check(MessageKind kind, Compiler cachedCompiler,
+                       {bool expectNoHowToFix: false}) {
   if (expectNoHowToFix) {
     Expect.isNull(kind.howToFix);
   } else {
@@ -38,20 +39,21 @@ Compiler check(MessageKind kind, Compiler cachedCompiler,
         options: ['--analyze-only'],
         cachedCompiler: cachedCompiler);
 
-    compiler.run(Uri.parse('memory:main.dart'));
+    return compiler.run(Uri.parse('memory:main.dart')).then((_) {
 
-    Expect.isFalse(messages.isEmpty, 'No messages in """$example"""');
+      Expect.isFalse(messages.isEmpty, 'No messages in """$example"""');
 
-    String expectedText = kind.howToFix == null
-        ? kind.template : '${kind.template}\n${kind.howToFix}';
-    String pattern = expectedText.replaceAllMapped(
-        new RegExp(ESCAPE_REGEXP), (m) => '\\${m[0]}');
-    pattern = pattern.replaceAll(new RegExp(r'#\\\{[^}]*\\\}'), '.*');
+      String expectedText = kind.howToFix == null
+          ? kind.template : '${kind.template}\n${kind.howToFix}';
+      String pattern = expectedText.replaceAllMapped(
+          new RegExp(ESCAPE_REGEXP), (m) => '\\${m[0]}');
+      pattern = pattern.replaceAll(new RegExp(r'#\\\{[^}]*\\\}'), '.*');
 
-    for (String message in messages) {
-      Expect.isTrue(new RegExp('^$pattern\$').hasMatch(message),
-                    '"$pattern" does not match "$message"');
-    }
-    return compiler;
+      for (String message in messages) {
+        Expect.isTrue(new RegExp('^$pattern\$').hasMatch(message),
+                      '"$pattern" does not match "$message"');
+      }
+      return compiler;
+    });
   }
 }