Use task model for strong mode

lib/src/driver.dart

Index: lib/src/driver.dart
diff --git a/lib/src/driver.dart b/lib/src/driver.dart
index 925dcf69eb671de50cb9fb036e69bdd332451273..37968dd2617ef713a24b8fe88f438421e05105ee 100644
--- a/lib/src/driver.dart
+++ b/lib/src/driver.dart
@@ -366,7 +366,7 @@ class Driver {
     // that.
     // TODO(paulberry): simplify this logic when strong mode supports the new
     // task model.
-    if (options.strongMode || options.disableNewTaskModel) {
+    if (options.disableNewTaskModel) {
       AnalysisEngine.instance.useTaskModel = false;
     } else {
       AnalysisEngine.instance.useTaskModel = true;
@@ -410,6 +410,7 @@ class Driver {
     contextOptions.generateImplicitErrors = options.showPackageWarnings;
     contextOptions.generateSdkErrors = options.showSdkWarnings;
     contextOptions.lint = options.lints;
+    contextOptions.strongMode = options.strongMode;
     context.analysisOptions = contextOptions;
     _context = context;