a few small refactorings to closure workarounds

lib/src/codegen/js_printer.dart

 // Copyright (c) 2015, 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 'dart:convert' show JSON, JsonEncoder;
 import 'dart:io' show Directory, File, Platform, Process;
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:path/path.dart' as path;
 import 'package:source_maps/source_maps.dart' as srcmaps show Printer;
 import 'package:source_maps/source_maps.dart' show SourceMapSpan;
 import 'package:source_span/source_span.dart' show SourceLocation;
 
 import '../js/js_ast.dart' as JS;
 import '../utils.dart' show FileSystem, computeHash, locationForOffset;
 
 import 'js_names.dart' show TemporaryNamer;
 
 String writeJsLibrary(
     JS.Program jsTree, String outputPath, String inputDir, Uri serverUri,
-    {bool emitSourceMaps: false, FileSystem fileSystem}) {
+    {bool emitSourceMaps: false,
+    bool emitTypes: false,
+    FileSystem fileSystem}) {
   var outFilename = path.basename(outputPath);
   var outDir = path.dirname(outputPath);
 
   JS.JavaScriptPrintingContext context;
   if (emitSourceMaps) {
     var printer = new srcmaps.Printer(outFilename);
     context =
         new SourceMapPrintingContext(printer, outDir, inputDir, serverUri);
   } else {
     context = new JS.SimpleJavaScriptPrintingContext();
   }
 
   var opts = new JS.JavaScriptPrintingOptions(
-      shouldEmitTypes: true,
+      emitTypes: emitTypes,
       allowKeywordsInProperties: true,
       allowSingleLineIfStatements: true);
   var jsNamer = new TemporaryNamer(jsTree);
   jsTree.accept(new JS.Printer(opts, context, localNamer: jsNamer));
 
   String text;
   if (context is SourceMapPrintingContext) {
     var printer = context.printer;
     printer.add('//# sourceMappingURL=$outFilename.map\n');
     // Write output file and source map
     text = printer.text;
     var sourceMap = JSON.decode(printer.map);
+    // TODO(jmesserly): I'm not sure where this logic came from, but we should
+    // upstream this, rather than workaround source_map's formatting ourselves.
     var sourceMapText = new JsonEncoder.withIndent('  ').convert(sourceMap);
     // Convert:
     //   "names": [
     //     "state",
     //     "print"
     //   ]
     // to:
     //   "names": ["state","print"]
     sourceMapText =
         sourceMapText.replaceAll('\n    ', '').replaceAll('\n  ]', ']');
@@ skipping 86 matching lines @@
       _currentTopLevelDeclaration == null;
       return;
     }
   }
 
   String _getIdentifier(AstNode node) {
     if (node is SimpleIdentifier) return node.name;
     return null;
   }
 }