Fix 56 hints in pkg/compiler

pkg/compiler/lib/src/dump_info.dart

 // Copyright (c) 2013, 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.
 
 library dump_info;
 
 import 'dart:convert' show
     HtmlEscape,
     JsonEncoder,
     StringConversionSink,
@@ skipping 74 matching lines @@
   final GroupedIdMapper mapper = new GroupedIdMapper();
   final Compiler compiler;
 
   final Map<Element, Map<String, dynamic>> jsonCache = {};
 
   String dart2jsVersion;
 
   ElementToJsonVisitor(this.compiler);
 
   void run() {
-    Backend backend = compiler.backend;
-
     dart2jsVersion = compiler.hasBuildId ? compiler.buildId : null;
 
     for (LibraryElement library in compiler.libraryLoader.libraries.toList()) {
       visit(library);
     }
   }
 
   Map<String, dynamic> visit(Element e, [_]) => e.accept(this, null);
 
   // If keeping the element is in question (like if a function has a size
@@ skipping 182 matching lines @@
 
   Map<String, dynamic> visitFunctionElement(FunctionElement element, _) {
     String id = mapper._function.add(element);
     String name = element.name;
     String kind = "function";
     List<String> children = [];
     List<Map<String, dynamic>> parameters = [];
     String inferredReturnType = null;
     String returnType = null;
     String sideEffects = null;
-    String code = "";
 
     StringBuffer emittedCode = compiler.dumpInfoTask.codeOf(element);
     int size = compiler.dumpInfoTask.sizeOf(element);
 
     Map<String, dynamic> modifiers = {
       'static': element.isStatic,
       'const': element.isConst,
       'factory': element.isFactoryConstructor,
       'external': element.isPatched
     };
@@ skipping 242 matching lines @@
       dumpInfoJson(jsonBuffer);
       compiler.outputProvider('', 'info.json')
         ..add(jsonBuffer.toString())
         ..close();
     });
   }
 
 
   void dumpInfoJson(StringSink buffer) {
     JsonEncoder encoder = const JsonEncoder.withIndent('  ');
-    DateTime startToJsonTime = new DateTime.now();
+    var stopwatch = new Stopwatch();

[Johnni Winther, 2015/05/22 07:37:57]

'var' -> 'Stopwatch'

[kevmoo, 2015/05/22 15:39:01]

Done.

+    stopwatch.start();
 
     Map<String, List<Map<String, String>>> holding =
         <String, List<Map<String, String>>>{};
     for (Element fn in infoCollector.mapper.functions) {
       Iterable<Selection> pulling = getRetaining(fn);
       // Don't bother recording an empty list of dependencies.
       if (pulling.length > 0) {
         String fnId = infoCollector.idOf(fn);
         // Some dart2js builtin functions are not
         // recorded.  Don't register these.
@@ skipping 48 matching lines @@
       'elements': infoCollector.toJson(),
       'holding': holding,
       'outputUnits': outputUnits,
       'dump_version': 3,
       'deferredFiles': compiler.deferredLoadTask.computeDeferredMap(),
       // This increases when new information is added to the map, but the viewer
       // still is compatible.
       'dump_minor_version': '2'
     };
 
-    Duration toJsonDuration = new DateTime.now().difference(startToJsonTime);
-
     Map<String, dynamic> generalProgramInfo = <String, dynamic> {
       'size': _programSize,
       'dart2jsVersion': infoCollector.dart2jsVersion,
       'compilationMoment': new DateTime.now().toString(),
       'compilationDuration': compiler.totalCompileTime.elapsed.toString(),
-      'toJsonDuration': 0,
+      'toJsonDuration': stopwatch.elapsedMilliseconds,
       'dumpInfoDuration': this.timing.toString(),
       'noSuchMethodEnabled': backend.enabledNoSuchMethod,
       'minified': compiler.enableMinification
     };
 
     outJson['program'] = generalProgramInfo;
 
     ChunkedConversionSink<Object> sink =
       encoder.startChunkedConversion(
           new StringConversionSink.fromStringSink(buffer));
     sink.add(outJson);
     compiler.reportInfo(NO_LOCATION_SPANNABLE,
         const MessageKind(
             "View the dumped .info.json file at "
             "https://dart-lang.github.io/dump-info-visualizer"));
   }
 }