Refactor strong mode to use standard Analyzer errors

pkg/analyzer/lib/src/task/dart.dart

Index: pkg/analyzer/lib/src/task/dart.dart
diff --git a/pkg/analyzer/lib/src/task/dart.dart b/pkg/analyzer/lib/src/task/dart.dart
index 0ce72275c5eb349f93d3d568275cc8e1f6e8dcf4..541246b030970960ba0a0fdaf89dd5b08c657e95 100644
--- a/pkg/analyzer/lib/src/task/dart.dart
+++ b/pkg/analyzer/lib/src/task/dart.dart
@@ -5682,9 +5682,12 @@ class StrongModeVerifyUnitTask extends SourceBasedAnalysisTask {
     CompilationUnit unit = getRequiredInput(UNIT_INPUT);
     AnalysisOptionsImpl options = context.analysisOptions;
     if (options.strongMode) {
-      unit.accept(new CodeChecker(
-          typeProvider, new StrongTypeSystemImpl(), errorListener,
-          options));
+      CodeChecker checker = new CodeChecker(
+          typeProvider,
+          new StrongTypeSystemImpl(implicitCasts: options.implicitCasts),
+          errorListener,
+          options);
+      checker.visitCompilationUnit(unit);
     }
     //
     // Record outputs.