Fix a few unused imports and symbol warnings.

pkg/dev_compiler/lib/src/compiler/code_generator.dart

Index: pkg/dev_compiler/lib/src/compiler/code_generator.dart
diff --git a/pkg/dev_compiler/lib/src/compiler/code_generator.dart b/pkg/dev_compiler/lib/src/compiler/code_generator.dart
index 9b1c72fe7718123745657f34ee42af5a0433cf74..3eb6ab8588b5fb4e589e626e0b96c36033a3b442 100644
--- a/pkg/dev_compiler/lib/src/compiler/code_generator.dart
+++ b/pkg/dev_compiler/lib/src/compiler/code_generator.dart
@@ -9,8 +9,8 @@ import 'dart:math' show min, max;
 import 'package:analyzer/analyzer.dart' hide ConstantEvaluator;
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_ast_factory.dart';
-import 'package:analyzer/dart/ast/token.dart' show Token, TokenType;
 import 'package:analyzer/dart/ast/standard_resolution_map.dart';
+import 'package:analyzer/dart/ast/token.dart' show TokenType;
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/dart/ast/token.dart' show StringToken;
@@ -4705,12 +4705,6 @@ class CodeGenerator extends Object
     ]);
   }
 
-  static Token _getOperator(Expression node) {
-    if (node is PropertyAccess) return node.operator;
-    if (node is MethodInvocation) return node.operator;
-    return null;
-  }
-
   // TODO(jmesserly): this is dropping source location.
   Expression _stripNullAwareOp(Expression node, Expression newTarget) {
     if (node is PropertyAccess) {