Implement modular compilation

lib/src/analyzer/dart_sdk.dart

Index: lib/src/analyzer/dart_sdk.dart
diff --git a/lib/src/dart_sdk.dart b/lib/src/analyzer/dart_sdk.dart
similarity index 98%
rename from lib/src/dart_sdk.dart
rename to lib/src/analyzer/dart_sdk.dart
index 468a68bc9b5fd09b19d4a9f0e4f9132366b527ea..b12b9168aa94951e2527df1621c9b123dde317da 100644
--- a/lib/src/dart_sdk.dart
+++ b/lib/src/analyzer/dart_sdk.dart
@@ -18,12 +18,16 @@ import 'package:analyzer/src/context/cache.dart'
 
 /// Dart SDK which contains a mock implementation of the SDK libraries. May be
 /// used to speed up execution when most of the core libraries is not needed.
+//
+// TODO(jmesserly): replace this with Analyzer's mock SDK, or use summaries
+// to load the real SDK.
 class MockDartSdk implements DartSdk {
   final Map<Uri, _MockSdkSource> _sources = {};
   final bool reportMissing;
   final Map<String, SdkLibrary> _libs = {};
   final String sdkVersion = '0';
   List<String> get uris => _sources.keys.map((uri) => '$uri').toList();
+
   AnalysisContext context;
   DartUriResolver _resolver;
   DartUriResolver get resolver => _resolver;