Rewire DDC to use the analyzer task model

lib/strong_mode.dart

Index: lib/strong_mode.dart
diff --git a/lib/strong_mode.dart b/lib/strong_mode.dart
index 16fbdf8f141822ddb55a60324b2ed62e6ea572ad..526efee1cdb7c38d6bb48a4b640964e256ecbf39 100644
--- a/lib/strong_mode.dart
+++ b/lib/strong_mode.dart
@@ -7,7 +7,7 @@
 library dev_compiler.strong_mode;
 
 import 'package:analyzer/src/generated/engine.dart'
-    show AnalysisContextImpl, AnalysisErrorInfo, AnalysisErrorInfoImpl;
+    show AnalysisContext, AnalysisContextImpl, AnalysisEngine, AnalysisErrorInfo, AnalysisErrorInfoImpl;
 import 'package:analyzer/src/generated/error.dart'
     show
         AnalysisError,
@@ -27,15 +27,15 @@ import 'src/checker/rules.dart' show RestrictedRules;
 /// A type checker for Dart code that operates under stronger rules, and has
 /// the ability to do local type inference in some situations.
 class StrongChecker {
-  final AnalysisContextImpl _context;
+  final AnalysisContext _context;
   final CodeChecker _checker;
   final _ErrorCollector _reporter;
 
   StrongChecker._(this._context, this._checker, this._reporter);
 
   factory StrongChecker(
-      AnalysisContextImpl context, StrongModeOptions options) {
-    enableDevCompilerInference(context, options);
+      AnalysisContext context, StrongModeOptions options) {
+    if (!AnalysisEngine.instance.useTaskModel) enableDevCompilerInference(context, options);
     var rules = new RestrictedRules(context.typeProvider, options: options);
     var reporter = new _ErrorCollector(options.hints);
     var checker = new CodeChecker(rules, reporter, options);