Fix hints reported by analyzer.

pkg/compiler/lib/src/ssa/builder_kernel.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:kernel/ast.dart' as ir;
 
 import '../closure.dart';
 import '../common.dart';
 import '../common/codegen.dart' show CodegenRegistry, CodegenWorkItem;
 import '../common/names.dart';
 import '../common/tasks.dart' show CompilerTask;
 import '../compiler.dart';
 import '../constants/values.dart'
     show
         ConstantValue,
         InterceptorConstantValue,
         StringConstantValue,
         TypeConstantValue;
 import '../elements/resolution_types.dart';
 import '../elements/elements.dart';
 import '../io/source_information.dart';
 import '../js/js.dart' as js;
 import '../js_backend/backend.dart' show JavaScriptBackend;
 import '../kernel/kernel.dart';
 import '../native/native.dart' as native;
 import '../resolution/tree_elements.dart';
 import '../tree/dartstring.dart';
-import '../tree/nodes.dart' show Node, BreakStatement;
+import '../tree/nodes.dart' show Node;
 import '../types/masks.dart';
 import '../universe/call_structure.dart' show CallStructure;
 import '../universe/selector.dart';
 import '../universe/side_effects.dart' show SideEffects;
 import '../universe/use.dart' show StaticUse;
 import '../world.dart';
 import 'graph_builder.dart';
 import 'jump_handler.dart';
 import 'kernel_ast_adapter.dart';
 import 'kernel_string_builder.dart';
@@ skipping 551 matching lines @@
   @override
   void visitReturnStatement(ir.ReturnStatement returnStatement) {
     HInstruction value;
     if (returnStatement.expression == null) {
       value = graph.addConstantNull(closedWorld);
     } else {
       assert(_targetFunction != null && _targetFunction is ir.FunctionNode);
       returnStatement.expression.accept(this);
       value = pop();
       if (_targetFunction.asyncMarker == ir.AsyncMarker.Async) {
-        var returnType = astAdapter.getDartType(_targetFunction.returnType);
+        astAdapter.getDartType(_targetFunction.returnType);

[Siggi Cherem (dart-lang), 2017/01/20 18:12:32]

you can delete the entire line here

[ahe, 2017/01/23 10:58:36]

Done.

         if (compiler.options.enableTypeAssertions &&
             !isValidAsyncReturnType(_targetFunction.returnType)) {
           generateTypeError(
               returnStatement,
               "Async function returned a Future,"
               " was declared to return a ${_targetFunction.returnType}.");
           pop();
           return;
         }
       } else {
@@ skipping 626 matching lines @@
   @override
   void visitSwitchStatement(ir.SwitchStatement switchStatement) {
     Map<ir.Expression, ConstantValue> constants =
         _buildSwitchCaseConstants(switchStatement);
 
     // The switch case indices must match those computed in
     // [KernelSwitchCaseJumpHandler].
     bool hasContinue = false;
     Map<ir.SwitchCase, int> caseIndex = new Map<ir.SwitchCase, int>();
     int switchIndex = 1;
-    bool hasDefault = false;
     for (ir.SwitchCase switchCase in switchStatement.cases) {
       if (SwitchContinueAnalysis.containsContinue(switchCase.body)) {
         hasContinue = true;
       }
-      if (switchCase.isDefault) {
-        hasDefault = true;
-      }
       caseIndex[switchCase] = switchIndex;
       switchIndex++;
     }
 
     JumpHandler jumpHandler = createJumpHandler(switchStatement);
     if (!hasContinue) {
       // If the switch statement has no switch cases targeted by continue
       // statements we encode the switch statement directly.
       _buildSimpleSwitchStatement(switchStatement, jumpHandler, constants);
     } else {
@@ skipping 1614 matching lines @@
     enterBlock.setBlockFlow(
         new HTryBlockInformation(
             kernelBuilder.wrapStatementGraph(bodyGraph),
             exception,
             kernelBuilder.wrapStatementGraph(catchGraph),
             kernelBuilder.wrapStatementGraph(finallyGraph)),
         exitBlock);
     kernelBuilder.inTryStatement = previouslyInTryStatement;
   }
 }