Create and test source mapping for invocations.

pkg/compiler/lib/src/compiler.dart

Index: pkg/compiler/lib/src/compiler.dart
diff --git a/pkg/compiler/lib/src/compiler.dart b/pkg/compiler/lib/src/compiler.dart
index 88368dd5bfc42c99f764193586f22810a87e7e9c..e8fdf36d61835c5e296e6e0d986de03966df7448 100644
--- a/pkg/compiler/lib/src/compiler.dart
+++ b/pkg/compiler/lib/src/compiler.dart
@@ -272,6 +272,11 @@ abstract class Backend {
   /// Backend callback methods for the resolution phase.
   ResolutionCallbacks get resolutionCallbacks;
 
+  /// The strategy used for collecting and emitting source information.
+  SourceInformationStrategy get sourceInformationStrategy {
+    return const SourceInformationStrategy();
+  }
+
   // TODO(johnniwinther): Move this to the JavaScriptBackend.
   String get patchVersion => null;
 
@@ -1093,17 +1098,10 @@ abstract class Compiler implements DiagnosticListener {
     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, sourceInformationFactory, generateSourceMap: generateSourceMap);
+      js_backend.JavaScriptBackend jsBackend =
+          new js_backend.JavaScriptBackend(
+              this, generateSourceMap: generateSourceMap);
       backend = jsBackend;
     } else {
       backend = new dart_backend.DartBackend(this, strips,
@@ -1122,7 +1120,7 @@ abstract class Compiler implements DiagnosticListener {
       resolver = new ResolverTask(this, backend.constantCompilerTask),
       closureToClassMapper = new closureMapping.ClosureTask(this),
       checker = new TypeCheckerTask(this),
-      irBuilder = new IrBuilderTask(this, sourceInformationFactory),
+      irBuilder = new IrBuilderTask(this, backend.sourceInformationStrategy),
       typesTask = new ti.TypesTask(this),
       constants = backend.constantCompilerTask,
       deferredLoadTask = new DeferredLoadTask(this),