First pass at asynchronous input loading in dart2js.

tests/compiler/dart2js/gvn_dynamic_field_get_test.dart

Index: tests/compiler/dart2js/gvn_dynamic_field_get_test.dart
diff --git a/tests/compiler/dart2js/gvn_dynamic_field_get_test.dart b/tests/compiler/dart2js/gvn_dynamic_field_get_test.dart
index c1a784a38625d6ffccf149afae0ee3748966051f..df93bb342b732af54808ca02b679a792be8fbd6c 100644
--- a/tests/compiler/dart2js/gvn_dynamic_field_get_test.dart
+++ b/tests/compiler/dart2js/gvn_dynamic_field_get_test.dart
@@ -24,16 +24,17 @@ main() {
 main() {
   Uri uri = new Uri(scheme: 'source');
   var compiler = compilerFor(TEST, uri);
-  compiler.runCompiler(uri);
-  String generated = compiler.assembledCode;
-  RegExp regexp = new RegExp(r"get\$foo");
-  Iterator matches = regexp.allMatches(generated).iterator;
-  checkNumberOfMatches(matches, 1);
-  var cls = findElement(compiler, 'A');
-  Expect.isNotNull(cls);
-  SourceString name = buildSourceString('foo');
-  var element = cls.lookupLocalMember(name);
-  Expect.isNotNull(element);
-  Selector selector = new Selector.getter(name, null);
-  Expect.isFalse(compiler.world.hasAnyUserDefinedGetter(selector));
+  compiler.runCompiler(uri).then((_) {
+    String generated = compiler.assembledCode;
+    RegExp regexp = new RegExp(r"get\$foo");
+    Iterator matches = regexp.allMatches(generated).iterator;
+    checkNumberOfMatches(matches, 1);
+    var cls = findElement(compiler, 'A');
+    Expect.isNotNull(cls);
+    SourceString name = buildSourceString('foo');
+    var element = cls.lookupLocalMember(name);
+    Expect.isNotNull(element);
+    Selector selector = new Selector.getter(name, null);
+    Expect.isFalse(compiler.world.hasAnyUserDefinedGetter(selector));
+  });
 }