Make source information on conditions mandatory in CPS

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

Index: pkg/compiler/lib/src/io/source_information.dart
diff --git a/pkg/compiler/lib/src/io/source_information.dart b/pkg/compiler/lib/src/io/source_information.dart
index fb02260119bd1eb948c180e9dbfb5da3d1211eb4..8a24759a83ef141586450faed31da21325f71929 100644
--- a/pkg/compiler/lib/src/io/source_information.dart
+++ b/pkg/compiler/lib/src/io/source_information.dart
@@ -141,6 +141,12 @@ class SourceInformationBuilder {
 
   /// Generate [SourceInformation] for the as-cast in [node].
   SourceInformation buildAs(Node node) => null;
+
+  /// Generate [SourceInformation] for the switch statement [node].
+  SourceInformation buildSwitch(Node node) => null;
+
+  /// Generate [SourceInformation] for the switch case in [node].
+  SourceInformation buildSwitchCase(Node node) => null;
 }
 
 /// A location in a source file.