Replace dart_core.js with actual compiled SDK

lib/src/options.dart

 // Copyright (c) 2014, 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.
 
 /// Set of flags and options passed to the compiler
 library dev_compiler.src.options;
 
 import 'dart:io';
 
 import 'package:args/args.dart';
@@ skipping 175 matching lines @@
   final List<String> nonnullableTypes;
 
   /// Whether to use static types for code generation.
   @override
   final bool ignoreTypes;
 
   /// Whether to emit the source map files.
   @override
   final bool emitSourceMaps;
 
-  /// Location for runtime files, such as `dart_core.js`. By default this is
+  /// Location for runtime files, such as `dart_runtime.js`. By default this is
   /// inferred to be under `lib/runtime/` in the location of the `dev_compiler`
   /// package (if we can infer where that is located).
   final String runtimeDir;
 
   CompilerOptions({this.allowConstCasts: true, this.checkSdk: false,
       this.dumpInfo: false, this.dumpInfoFile, this.dumpSrcDir,
       this.forceCompile: false, this.formatOutput: false,
       this.cheapTestFormat: false, this.ignoreTypes: false, this.outputDir,
       this.outputDart: false, this.useColors: true,
       this.covariantGenerics: true, this.relaxedCasts: true,
@@ skipping 165 matching lines @@
     // The pub-cache directory is two levels up, but we verify that the layout
     // looks correct.
     if (path.basename(dir) != 'dev_compiler') return null;
     dir = path.dirname(dir);
     if (path.basename(dir) != 'global_packages') return null;
     dir = path.dirname(dir);
     return path.join(dir, cacheDir, 'lib', 'runtime');
   }
   return null;
 }