Introduce a testing framework for use with fasta type inference.

pkg/front_end/lib/src/fasta/source/source_loader.dart

Index: pkg/front_end/lib/src/fasta/source/source_loader.dart
diff --git a/pkg/front_end/lib/src/fasta/source/source_loader.dart b/pkg/front_end/lib/src/fasta/source/source_loader.dart
index dfb6c87f9d5b8da020033120a9bfcae9e650de59..e367dd2830849f3c08714df4b21257006106369b 100644
--- a/pkg/front_end/lib/src/fasta/source/source_loader.dart
+++ b/pkg/front_end/lib/src/fasta/source/source_loader.dart
@@ -8,6 +8,8 @@ import 'dart:async' show Future;
 
 import 'dart:typed_data' show Uint8List;
 
+import 'package:front_end/src/base/instrumentation.dart' show Instrumentation;
+
 import 'package:front_end/src/fasta/kernel/kernel_shadow_ast.dart'
     show KernelTypeInferrer;
 
@@ -53,6 +55,8 @@ class SourceLoader<L> extends Loader<L> {
   ClassHierarchy hierarchy;
   CoreTypes coreTypes;
 
+  Instrumentation instrumentation;
+
   SourceLoader(TargetImplementation target) : super(target);
 
   Future<Token> tokenize(SourceLibraryBuilder library,
@@ -123,7 +127,7 @@ class SourceLoader<L> extends Loader<L> {
 
   DietListener createDietListener(LibraryBuilder library) {
     return new DietListener(library, hierarchy, coreTypes,
-        new KernelTypeInferrer(coreTypes, hierarchy));
+        new KernelTypeInferrer(coreTypes, hierarchy, instrumentation));
   }
 
   void resolveParts() {