Remove redundancy in source map entries.

sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart

 // Copyright (c) 2012, 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.
 
 part of dart2js.js_emitter;
 
 /**
  * Generates the code for all used classes in the program. Static fields (even
  * in classes) are ignored, since they can be treated as non-class elements.
  *
@@ skipping 1678 matching lines @@
     return '// Generated by dart2js, the Dart to JavaScript compiler$suffix.\n';
   }
 
   void outputSourceMap(String code, CodeBuffer buffer, String name,
                        [Uri sourceMapUri, Uri fileUri]) {
     if (!generateSourceMap) return;
     // Create a source file for the compilation output. This allows using
     // [:getLine:] to transform offsets to line numbers in [SourceMapBuilder].
     SourceFile compiledFile = new StringSourceFile(null, code);
     SourceMapBuilder sourceMapBuilder =
-            new SourceMapBuilder(sourceMapUri, fileUri);
+            new SourceMapBuilder(sourceMapUri, fileUri, compiledFile);
     buffer.forEachSourceLocation(sourceMapBuilder.addMapping);
-    String sourceMap = sourceMapBuilder.build(compiledFile);
+    String sourceMap = sourceMapBuilder.build();
     compiler.outputProvider(name, 'js.map')
         ..add(sourceMap)
         ..close();
   }
 
   void registerReadTypeVariable(TypeVariableElement element) {
     readTypeVariables.add(element);
   }
 }