Add _sdkext support back to analysis server

pkg/analysis_server/lib/src/context_manager.dart

Index: pkg/analysis_server/lib/src/context_manager.dart
diff --git a/pkg/analysis_server/lib/src/context_manager.dart b/pkg/analysis_server/lib/src/context_manager.dart
index 2d4d08faed6b2d8ccdea7b518c133d63c69f517f..c9502d62d0822448362c994dce3f3eb6e5cf5276 100644
--- a/pkg/analysis_server/lib/src/context_manager.dart
+++ b/pkg/analysis_server/lib/src/context_manager.dart
@@ -19,6 +19,7 @@ import 'package:analyzer/source/package_map_provider.dart';
 import 'package:analyzer/source/package_map_resolver.dart';
 import 'package:analyzer/source/path_filter.dart';
 import 'package:analyzer/source/pub_package_map_provider.dart';
+import 'package:analyzer/source/sdk_ext.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/java_io.dart';
 import 'package:analyzer/src/generated/source.dart';
@@ -1352,7 +1353,8 @@ class PackageMapDisposition extends FolderDisposition {
   @override
   Iterable<UriResolver> createPackageUriResolvers(
           ResourceProvider resourceProvider) =>
-      <UriResolver>[new PackageMapUriResolver(resourceProvider, packageMap)];
+      <UriResolver>[new SdkExtUriResolver(packageMap),
+                    new PackageMapUriResolver(resourceProvider, packageMap)];
 }
 
 /**
@@ -1370,6 +1372,19 @@ class PackagesFileDisposition extends FolderDisposition {
 
   @override
   Iterable<UriResolver> createPackageUriResolvers(
-          ResourceProvider resourceProvider) =>
-      const <UriResolver>[];
+          ResourceProvider resourceProvider) {
+    if (packages != null) {
+      // Construct package map for the SdkExtUriResolver.
+      Map<String, List<Folder>> packageMap = <String, List<Folder>>{};
+      packages.asMap().forEach((String name, Uri uri) {
+        if (uri.scheme == 'file' || uri.scheme == '' /* unspecified */) {
+          packageMap[name] =
+              <Folder>[resourceProvider.getFolder(uri.toFilePath())];

[Paul Berry, 2015/08/13 17:12:07]

This will cause unit testing problems because uri.toFilePath() chooses whether
to create a Windows or a Posix file path based on the OS, but in unit tests we
override this sometimes.  Use resourceProvider.pathContext.fromUri(uri) instead.

[Cutch, 2015/08/13 19:24:17]

Done.

+        }
+      });
+      return <UriResolver>[new SdkExtUriResolver(packageMap)];
+    } else {
+      return const <UriResolver>[];
+    }
+  }
 }