Fixes #179 -- compile error if editing files during server mode

lib/src/codegen/code_generator.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.code_generator;
 
 import 'dart:io';
 
 import 'package:analyzer/src/generated/ast.dart' show CompilationUnit;
 import 'package:analyzer/src/generated/element.dart'
     show CompilationUnitElement, LibraryElement;
+import 'package:analyzer/src/generated/engine.dart' show AnalysisContext;
 import 'package:path/path.dart' as path;
 
+import 'package:dev_compiler/devc.dart' show CompilerContext;
 import 'package:dev_compiler/src/info.dart';
 import 'package:dev_compiler/src/utils.dart' show canonicalLibraryName;
 import 'package:dev_compiler/src/checker/rules.dart';
+import 'package:dev_compiler/src/options.dart';
 
 abstract class CodeGenerator {
+  final CompilerContext compiler;
   final String outDir;
   final Uri root;
   final TypeRules rules;
+  final AnalysisContext context;
+  final CompilerOptions options;
+
+  CodeGenerator(CompilerContext compiler)
+      : compiler = compiler,
+        outDir = path.absolute(compiler.options.outputDir),
+        root = compiler.entryPointUri,
+        rules = compiler.rules,
+        context = compiler.context,
+        options = compiler.options;
+
+  /// Return a hash, if any, that can be used for caching purposes. When two
+  /// invocations to this function return the same hash, the underlying
+  /// code-generator generated the same code.
+  String generateLibrary(LibraryUnit unit, LibraryInfo info);
 
   static List<String> _searchPaths = () {
     // TODO(vsm): Can we remove redundancy with multi_package_resolver logic?
     var packagePaths =
         new String.fromEnvironment('package_paths', defaultValue: null);
     if (packagePaths == null) return null;
     var list = packagePaths.split(',');
     // Normalize the paths.
     list = new List<String>.from(list.map(_dirToPrefix));
     // The current directory is implicitly in the search path.
@@ skipping 85 matching lines @@
     if (index < 0) {
       // Not a package.
       // TODO(leafp) These may need to be adjusted
       // relative to the import location
       return new Uri(path: suffix);
     }
     assert(index == 0);
     return new Uri(
         scheme: 'package', path: path.joinAll(parts.sublist(index + 1)));
   }
-
-  CodeGenerator(String outDir, this.root, this.rules)
-      : outDir = path.absolute(outDir);
-
-  /// Return a hash, if any, that can be used for caching purposes. When two
-  /// invocations to this function return the same hash, the underlying
-  /// code-generator generated the same code.
-  String generateLibrary(LibraryUnit unit, LibraryInfo info);
 }