Pass SourceInformation through the CPS IR.

pkg/compiler/lib/src/io/code_output.dart

Index: pkg/compiler/lib/src/io/code_output.dart
diff --git a/pkg/compiler/lib/src/io/code_output.dart b/pkg/compiler/lib/src/io/code_output.dart
index d046f2242a50025c403984b68cae5d28e98e2c60..8566f23c21f99de5abaf69b893efed585ebcaac7 100644
--- a/pkg/compiler/lib/src/io/code_output.dart
+++ b/pkg/compiler/lib/src/io/code_output.dart
@@ -41,6 +41,9 @@ abstract class CodeOutput {
   /// Closes the output. Further writes will cause a [StateError].
   void close();
 
+  /// Sets the [sourcePosition] for the code next added to this output.
+  void setSourceLocation(SourceLocation sourcePosition);
+
   /// Applies [f] to every marker in this output.
   void forEachSourceLocation(void f(int targetOffset,
                                     SourceLocation sourceLocation));