Merge libv1.

sdk/lib/_internal/compiler/compiler.dart

Index: sdk/lib/_internal/compiler/compiler.dart
diff --git a/sdk/lib/_internal/compiler/compiler.dart b/sdk/lib/_internal/compiler/compiler.dart
index 258a8b430d5cb9ee62a2154f00ebf33cd0808c04..af37116e0c2f886f24101922d9fe9355027b2617 100644
--- a/sdk/lib/_internal/compiler/compiler.dart
+++ b/sdk/lib/_internal/compiler/compiler.dart
@@ -2,10 +2,10 @@
 // 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.
 
-#library('compiler');
+library compiler;
 
-#import('dart:uri');
-#import('implementation/apiimpl.dart');
+import 'dart:uri';
+import 'implementation/apiimpl.dart';
 
 // Unless explicitly allowed, passing [:null:] for any argument to the
 // methods of library will result in a NullPointerException being
@@ -43,6 +43,12 @@ Future<String> compile(Uri script,
                        ReadStringFromUri provider,
                        DiagnosticHandler handler,
                        [List<String> options = const []]) {
+  if (!libraryRoot.path.endsWith("/")) {
+    throw new ArgumentError("libraryRoot must end with a /");
+  }
+  if (packageRoot != null && !packageRoot.path.endsWith("/")) {
+    throw new ArgumentError("packageRoot must end with a /");
+  }
   // TODO(ahe): Consider completing the future with an exception if
   // code is null.
   Compiler compiler = new Compiler(provider, handler, libraryRoot, packageRoot,