First pass at asynchronous input loading in dart2js.

tests/compiler/dart2js/resolver_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import "package:expect/expect.dart";
+import 'dart:async';
 import 'dart:collection';
 
 import "../../../sdk/lib/_internal/compiler/implementation/resolution/resolution.dart";
 import "compiler_helper.dart";
 import "parser_helper.dart";
 
 import '../../../sdk/lib/_internal/compiler/implementation/dart_types.dart';
 
 Node buildIdentifier(String name) => new Identifier(scan(name));
 
@@ skipping 760 matching lines @@
 
 at(Link link, int index) => (index == 0) ? link.head : at(link.tail, index - 1);
 
 List<String> asSortedStrings(Link link) {
   List<String> result = <String>[];
   for (; !link.isEmpty; link = link.tail) result.add(link.head.toString());
   result.sort((s1, s2) => s1.compareTo(s2));
   return result;
 }
 
-compileScript(String source) {
+Future compileScript(String source) {
   Uri uri = new Uri(scheme: 'source');
   MockCompiler compiler = compilerFor(source, uri);
-  compiler.runCompiler(uri);
-  return compiler;
+  return compiler.runCompiler(uri).then((_) {
+    return compiler;
+  });
 }
 
 checkMemberResolved(compiler, className, memberName) {
   Element memberElement = findElement(compiler, className)
       .lookupLocalMember(memberName);
   Expect.isNotNull(memberElement);
   Expect.isNotNull(
       compiler.enqueuer.resolution.getCachedElements(memberElement));
 }
 
 testToString() {
   final script = r"class C { toString() => 'C'; } main() { '${new C()}'; }";
-  final compiler = compileScript(script);
-
-  checkMemberResolved(compiler, 'C', buildSourceString('toString'));
+  compileScript(script).then((compiler) {
+    checkMemberResolved(compiler, 'C', buildSourceString('toString'));
+  });
 }
 
 operatorName(op, isUnary) {
   return Elements.constructOperatorName(new SourceString(op), isUnary);
 }
 
 testIndexedOperator() {
   final script = r"""
       class C {
         operator[](ix) => ix;
         operator[]=(ix, v) {}
       }
       main() { var c = new C(); c[0]++; }""";
-  final compiler = compileScript(script);
-
-  checkMemberResolved(compiler, 'C', operatorName('[]', false));
-  checkMemberResolved(compiler, 'C', operatorName('[]=', false));
+  compileScript(script).then((compiler) {
+    checkMemberResolved(compiler, 'C', operatorName('[]', false));
+    checkMemberResolved(compiler, 'C', operatorName('[]=', false));
+  });
 }
 
 testIncrementsAndDecrements() {
   final script = r"""
       class A { operator+(o)=>null; }
       class B { operator+(o)=>null; }
       class C { operator-(o)=>null; }
       class D { operator-(o)=>null; }
       main() {
         var a = new A();
         a++;
         var b = new B();
         ++b;
         var c = new C();
         c--;
         var d = new D();
         --d;
       }""";
-  final compiler = compileScript(script);
-
-  checkMemberResolved(compiler, 'A', operatorName('+', false));
-  checkMemberResolved(compiler, 'B', operatorName('+', false));
-  checkMemberResolved(compiler, 'C', operatorName('-', false));
-  checkMemberResolved(compiler, 'D', operatorName('-', false));
+  compileScript(script).then((compiler) {
+    checkMemberResolved(compiler, 'A', operatorName('+', false));
+    checkMemberResolved(compiler, 'B', operatorName('+', false));
+    checkMemberResolved(compiler, 'C', operatorName('-', false));
+    checkMemberResolved(compiler, 'D', operatorName('-', false));
+  });
 }