Inline source maps as part of each script.

pkg/dev_compiler/lib/src/compiler/compiler.dart

 // Copyright (c) 2016, 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:collection' show HashSet, Queue;
 import 'dart:convert' show BASE64, JSON, UTF8;
 import 'dart:io' show File;
 
 import 'package:analyzer/analyzer.dart'
     show AnalysisError, CompilationUnit, ErrorSeverity;
@@ skipping 491 matching lines @@
                 path.relative(path.fromUri(mapUrl), from: path.dirname(jsUrl)))
             .toString();
         assert(path.dirname(jsUrl) == path.dirname(mapUrl));
         printer.emit('\n//# sourceMappingURL=');
         printer.emit(relativeMapUrl);
         printer.emit('\n');
       }
     }
 
     var text = printer.getText();
-    var rawSourceMap = options.inlineSourceMap ? JSON.encode(builtMap) : null;
+    var rawSourceMap = 'null';
+    if (options.inlineSourceMap) {
+      var bytes = UTF8.encode(JSON.encode(builtMap));
+      // Base64 encode instead of json escaping to work around V8 bug
+      // unescaping strings with a large number of slashes.
+      rawSourceMap = "'${BASE64.encode(bytes)}'";
+    }
     // Encode the sourcemap as an escaped string rather than JSON
     // as Dart code using the sourcemap can't take advantage of it being JS
     // JSON so we might as well encode it as a String which should be quicker
     // to parse.
-    text = text.replaceFirst(sourceMapHoleID, JSON.encode(rawSourceMap));
+    text = text.replaceFirst(sourceMapHoleID, rawSourceMap);
 
     return new JSModuleCode(text, builtMap);
   }
 
   /// Similar to [getCode] but immediately writes the resulting files.
   ///
   /// If [mapPath] is not supplied but [options.sourceMap] is set, mapPath
   /// will default to [jsPath].map.
   void writeCodeSync(ModuleFormat format, String jsPath,
       {bool singleOutFile: false}) {
@@ skipping 75 matching lines @@
 /// are implementation details that would just confuse users.
 /// Normalize sdk urls to use "dart:" for more understandable stack traces.
 Map cleanupSdkSourcemap(Map sourceMap) {
   var map = new Map.from(sourceMap);
   var list = new List.from(map['sources']);
   map['sources'] = map['sources']
       .map((url) => url.contains('/_internal/') ? null : url)
       .toList();
   return map;
 }