Support source maps in server mode

lib/src/codegen/js_codegen.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.
 
 library dev_compiler.src.codegen.js_codegen;
 
 import 'dart:collection' show HashSet, HashMap, SplayTreeSet;
 
 import 'package:analyzer/analyzer.dart' hide ConstantEvaluator;
 import 'package:analyzer/src/generated/ast.dart' hide ConstantEvaluator;
@@ skipping 3570 matching lines @@
   String generateLibrary(LibraryUnit unit) {
     // Clone the AST first, so we can mutate it.
     unit = unit.clone();
     var library = unit.library.element.library;
     var fields = findFieldsNeedingStorage(unit, _extensionTypes);
     var rules = new StrongTypeSystemImpl();
     var codegen =
         new JSCodegenVisitor(compiler, rules, library, _extensionTypes, fields);
     var module = codegen.emitLibrary(unit);
     var out = compiler.getOutputPath(library.source.uri);
-    return writeJsLibrary(module, out,
+    var flags = compiler.options;
+    var serverUri = flags.serverMode
+        ? Uri.parse('http://${flags.host}:${flags.port}/')
+        : null;
+    return writeJsLibrary(module, out, compiler.inputBaseDir, serverUri,
         emitSourceMaps: options.emitSourceMaps,
         arrowFnBindThisWorkaround: options.arrowFnBindThisWorkaround);
   }
 }
 
 /// Choose a canonical name from the library element.
 /// This never uses the library's name (the identifier in the `library`
 /// declaration) as it doesn't have any meaningful rules enforced.
 String jsLibraryName(LibraryElement library) => canonicalLibraryName(library);
 
@@ skipping 10 matching lines @@
 
 /// A special kind of element created by the compiler, signifying a temporary
 /// variable. These objects use instance equality, and should be shared
 /// everywhere in the tree where they are treated as the same variable.
 class TemporaryVariableElement extends LocalVariableElementImpl {
   TemporaryVariableElement.forNode(Identifier name) : super.forNode(name);
 
   int get hashCode => identityHashCode(this);
   bool operator ==(Object other) => identical(this, other);
 }