First pass at asynchronous input loading in dart2js.

tests/compiler/dart2js/gvn_test.dart

Index: tests/compiler/dart2js/gvn_test.dart
diff --git a/tests/compiler/dart2js/gvn_test.dart b/tests/compiler/dart2js/gvn_test.dart
index 85bfad92583a4209f7fa62a3b6bf83b505cc1610..f5a1b4df5822bd9c7e5b7deb8551c3122fa0bf51 100644
--- a/tests/compiler/dart2js/gvn_test.dart
+++ b/tests/compiler/dart2js/gvn_test.dart
@@ -118,16 +118,20 @@ main() {
   generated = compile(TEST_FOUR, entry: 'foo');
   checkNumberOfMatches(new RegExp("shr").allMatches(generated).iterator, 1);
 
-  generated = compileAll(TEST_FIVE);
-  checkNumberOfMatches(
-      new RegExp("get\\\$foo").allMatches(generated).iterator, 1);
-
-  generated = compileAll(TEST_SIX);
-  Expect.isTrue(generated.contains('for (t1 = a.field === 54; t1;)'));
-
-  generated = compileAll(TEST_SEVEN);
-  Expect.isTrue(generated.contains('for (t1 = a.field === 54; t1;)'));
-
-  generated = compileAll(TEST_EIGHT);
-  Expect.isTrue(generated.contains('for (; i < t1; ++i)'));
+  compileAll(TEST_FIVE).then((generated) {
+    checkNumberOfMatches(
+        new RegExp("get\\\$foo").allMatches(generated).iterator, 1);
+  });
+
+  compileAll(TEST_SIX).then((generated) {
+    Expect.isTrue(generated.contains('for (t1 = a.field === 54; t1;)'));
+  });
+
+  compileAll(TEST_SEVEN).then((generated) {
+    Expect.isTrue(generated.contains('for (t1 = a.field === 54; t1;)'));
+  });
+
+  compileAll(TEST_EIGHT).then((generated) {
+    Expect.isTrue(generated.contains('for (; i < t1; ++i)'));
+  });
 }