[kernel] set dartAsyncMarker to Sync for continuations

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 a8b28205e7d446a47eaba6eb9ee6be33d804d52d..7f593d17f4efd7aec1278a23b1a6ce42a8f85822 100644
--- a/pkg/kernel/lib/transformations/continuation.dart
+++ b/pkg/kernel/lib/transformations/continuation.dart
@@ -124,11 +124,16 @@ class SyncStarFunctionRewriter extends ContinuationRewriterBase {
     // :sync_body(:iterator) {
     //     modified <node.body>;
     // }
+
+    // Note: SyncYielding functions have no Dart equivalent. Since they are
+    // synchronous, we use Sync. (Note also that the Dart VM backend uses the
+    // Dart async marker to decide if functions are debuggable.)
     final nestedClosureVariable = new VariableDeclaration(":sync_op");
     final function = new FunctionNode(buildClosureBody(),
         positionalParameters: [iteratorVariable],
         requiredParameterCount: 1,
-        asyncMarker: AsyncMarker.SyncYielding)
+        asyncMarker: AsyncMarker.SyncYielding,
+        dartAsyncMarker: AsyncMarker.Sync)
       ..fileOffset = enclosingFunction.fileOffset
       ..fileEndOffset = enclosingFunction.fileEndOffset
       ..returnType = helper.coreTypes.boolClass.rawType;
@@ -223,10 +228,15 @@ abstract class AsyncRewriterBase extends ContinuationRewriterBase {
       new VariableDeclaration(':exception'),
       new VariableDeclaration(':stack_trace'),
     ];
+
+    // Note: SyncYielding functions have no Dart equivalent. Since they are
+    // synchronous, we use Sync. (Note also that the Dart VM backend uses the
+    // Dart async marker to decide if functions are debuggable.)
     final function = new FunctionNode(buildWrappedBody(),
         positionalParameters: parameters,
         requiredParameterCount: 0,
-        asyncMarker: AsyncMarker.SyncYielding)
+        asyncMarker: AsyncMarker.SyncYielding,
+        dartAsyncMarker: AsyncMarker.Sync)
       ..fileOffset = enclosingFunction.fileOffset
       ..fileEndOffset = enclosingFunction.fileEndOffset;