Add SourceInformationFactory.

pkg/compiler/lib/src/compiler.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;
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
@@ skipping 1040 matching lines @@
 
     if (verbose) {
       progress = new Stopwatch()..start();
     }
 
     // TODO(johnniwinther): Separate the dependency tracking from the enqueueing
     // for global dependencies.
     globalDependencies =
         new CodegenRegistry(this, new TreeElementMapping(null));
 
+    SourceInformationFactory sourceInformationFactory =
+        const SourceInformationFactory();
+    if (generateSourceMap) {
+      sourceInformationFactory =
+          const bool.fromEnvironment('USE_NEW_SOURCE_INFO', defaultValue: false)
+              ? const PositionSourceInformationFactory()
+              : const StartEndSourceInformationFactory();
+    }
     if (emitJavaScript) {
-      js_backend.JavaScriptBackend jsBackend =
-          new js_backend.JavaScriptBackend(this, generateSourceMap);
+      js_backend.JavaScriptBackend jsBackend = new js_backend.JavaScriptBackend(
+      this, sourceInformationFactory, generateSourceMap: generateSourceMap);
       backend = jsBackend;
     } else {
       backend = new dart_backend.DartBackend(this, strips,
                                              multiFile: dart2dartMultiFile);
       if (dumpInfo) {
         throw new ArgumentError('--dump-info is not supported for dart2dart.');
       }
     }
 
     tasks = [
       libraryLoader = new LibraryLoaderTask(this),
       scanner = new ScannerTask(this),
       dietParser = new DietParserTask(this),
       parser = new ParserTask(this),
       patchParser = new PatchParserTask(this),
       resolver = new ResolverTask(this, backend.constantCompilerTask),
       closureToClassMapper = new closureMapping.ClosureTask(this),
       checker = new TypeCheckerTask(this),
-      irBuilder = new IrBuilderTask(this),
+      irBuilder = new IrBuilderTask(this, sourceInformationFactory),
       typesTask = new ti.TypesTask(this),
       constants = backend.constantCompilerTask,
       deferredLoadTask = new DeferredLoadTask(this),
       mirrorUsageAnalyzerTask = new MirrorUsageAnalyzerTask(this),
       enqueuer = new EnqueueTask(this),
       dumpInfoTask = new DumpInfoTask(this),
       reuseLibraryTask = new GenericTask('Reuse library', this),
     ];
 
     tasks.addAll(backend.tasks);
@@ skipping 1332 matching lines @@
     return futureClass.computeType(compiler).createInstantiation([elementType]);
   }
 
   @override
   InterfaceType streamType([DartType elementType = const DynamicType()]) {
     return streamClass.computeType(compiler).createInstantiation([elementType]);
   }
 }
 
 typedef void InternalErrorFunction(Spannable location, String message);