First pass at asynchronous input loading in dart2js.

tests/compiler/dart2js/resolution_test.dart

Index: tests/compiler/dart2js/resolution_test.dart
diff --git a/tests/compiler/dart2js/resolution_test.dart b/tests/compiler/dart2js/resolution_test.dart
index 32f59457a5f015ca4fa6efb6ce3e01460383c7ed..9f16059a5d188eeff715961df8a45252e2117ca3 100644
--- a/tests/compiler/dart2js/resolution_test.dart
+++ b/tests/compiler/dart2js/resolution_test.dart
@@ -94,8 +94,9 @@ main() {
 void test(String code, void check(Compiler compiler)) {
   Uri uri = new Uri(scheme: 'source');
   var compiler = compilerFor(code, uri);
-  compiler.runCompiler(uri);
-  check(compiler);
+  compiler.runCompiler(uri).then((_) {
+    check(compiler);
+  });
 }
 
 void testHasRuntimeType(String code) {