Split out options from ContextBuilder

pkg/dev_compiler/lib/src/analyzer/context.dart

Index: pkg/dev_compiler/lib/src/analyzer/context.dart
diff --git a/pkg/dev_compiler/lib/src/analyzer/context.dart b/pkg/dev_compiler/lib/src/analyzer/context.dart
index bc47716a6446c1650d642aa64ec50b227b638527..05bacf9c3f7546e2fa7a75b656d7df2b56ea164c 100644
--- a/pkg/dev_compiler/lib/src/analyzer/context.dart
+++ b/pkg/dev_compiler/lib/src/analyzer/context.dart
@@ -139,10 +139,12 @@ List<UriResolver> createFileResolvers(AnalyzerOptions options,
     {ResourceProvider resourceProvider}) {
   resourceProvider ??= PhysicalResourceProvider.INSTANCE;
   UriResolver packageResolver() {
-    ContextBuilder builder = new ContextBuilder(resourceProvider, null, null);
+    ContextBuilderOptions builderOptions = new ContextBuilderOptions();
     if (options.packageRoot != null) {
-      builder.defaultPackagesDirectoryPath = options.packageRoot;
+      builderOptions.defaultPackagesDirectoryPath = options.packageRoot;
     }
+    ContextBuilder builder = new ContextBuilder(resourceProvider, null, null,
+        options: builderOptions);
     return new PackageMapUriResolver(resourceProvider,
         builder.convertPackagesToMap(builder.createPackageMap('')));
   }