Switch on null-aware operators by default in analyzer.

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 ff5b0cb6e1e8907ab532a6e11d807ff3aab4e9e8..fa8daec4119a889465b5a188a541d190e7cf371b 100644
--- a/pkg/analyzer/lib/src/task/dart.dart
+++ b/pkg/analyzer/lib/src/task/dart.dart
@@ -3115,8 +3115,6 @@ class ScanDartTask extends SourceBasedAnalysisTask {
           errorListener);
       scanner.setSourceStart(fragment.line, fragment.column);
       scanner.preserveComments = context.analysisOptions.preserveComments;
-      scanner.enableNullAwareOperators =
-          context.analysisOptions.enableNullAwareOperators;
 
       outputs[TOKEN_STREAM] = scanner.tokenize();
       outputs[LINE_INFO] = new LineInfo(scanner.lineStarts);
@@ -3127,8 +3125,6 @@ class ScanDartTask extends SourceBasedAnalysisTask {
       Scanner scanner =
           new Scanner(source, new CharSequenceReader(content), errorListener);
       scanner.preserveComments = context.analysisOptions.preserveComments;
-      scanner.enableNullAwareOperators =
-          context.analysisOptions.enableNullAwareOperators;
 
       outputs[TOKEN_STREAM] = scanner.tokenize();
       outputs[LINE_INFO] = new LineInfo(scanner.lineStarts);