Transform async code only for source libraries.

pkg/kernel/lib/transformations/continuation.dart

Index: pkg/kernel/lib/transformations/continuation.dart
diff --git a/pkg/kernel/lib/transformations/continuation.dart b/pkg/kernel/lib/transformations/continuation.dart
index 72167987b2009382bbc9532e1c8ab8341261fc2e..4e4cdbba40809ca69de429db88538b34cbc7ddfa 100644
--- a/pkg/kernel/lib/transformations/continuation.dart
+++ b/pkg/kernel/lib/transformations/continuation.dart
@@ -12,6 +12,14 @@ import '../visitor.dart';
 
 import 'async.dart';
 
+void transformLibraries(CoreTypes coreTypes, List<Library> libraries) {
+  var helper = new HelperNodes.fromCoreTypes(coreTypes);
+  var rewriter = new RecursiveContinuationRewriter(helper);
+  for (var library in libraries) {
+    rewriter.rewriteLibrary(library);
+  }
+}
+
 Program transformProgram(Program program) {
   var helper = new HelperNodes.fromProgram(program);
   var rewriter = new RecursiveContinuationRewriter(helper);
@@ -32,6 +40,10 @@ class RecursiveContinuationRewriter extends Transformer {
     return node.accept(this);
   }
 
+  Library rewriteLibrary(Library node) {
+    return node.accept(this);
+  }
+
   visitFunctionNode(FunctionNode node) {
     switch (node.asyncMarker) {
       case AsyncMarker.Sync:
@@ -912,8 +924,7 @@ class HelperNodes {
       this.awaitHelper,
       this.coreTypes);
 
-  factory HelperNodes.fromProgram(Program program) {
-    var coreTypes = new CoreTypes(program);
+  factory HelperNodes.fromCoreTypes(CoreTypes coreTypes) {
     return new HelperNodes(
         coreTypes.asyncLibrary,
         coreTypes.coreLibrary,
@@ -932,4 +943,9 @@ class HelperNodes {
         coreTypes.awaitHelperProcedure,
         coreTypes);
   }
+
+  factory HelperNodes.fromProgram(Program program) {
+    var coreTypes = new CoreTypes(program);
+    return new HelperNodes.fromCoreTypes(coreTypes);
+  }
 }