[Kernel] replace function debuggable field with originalAsyncMarker field

pkg/kernel/lib/analyzer/ast_from_analyzer.dart

Index: pkg/kernel/lib/analyzer/ast_from_analyzer.dart
diff --git a/pkg/kernel/lib/analyzer/ast_from_analyzer.dart b/pkg/kernel/lib/analyzer/ast_from_analyzer.dart
index 45ebe7b996e3d444c6733dba546c37c28cde586f..8d8b30ba01e6862c85d90fbe172e79120471baf5 100644
--- a/pkg/kernel/lib/analyzer/ast_from_analyzer.dart
+++ b/pkg/kernel/lib/analyzer/ast_from_analyzer.dart
@@ -574,6 +574,8 @@ class ExpressionScope extends TypeScope {
     }
     int offset = formalParameters?.offset ?? body.offset;
     int endOffset = body.endToken.offset;
+    ast.AsyncMarker asyncMarker = getAsyncMarker(
+        isAsync: body.isAsynchronous, isStar: body.isGenerator);
     return new ast.FunctionNode(buildOptionalFunctionBody(body),
         typeParameters: typeParameters,
         positionalParameters: positional,
@@ -582,8 +584,8 @@ class ExpressionScope extends TypeScope {
         returnType: buildOptionalTypeAnnotation(returnType) ??
             inferredReturnType ??
             const ast.DynamicType(),
-        asyncMarker: getAsyncMarker(
-            isAsync: body.isAsynchronous, isStar: body.isGenerator))
+        asyncMarker: asyncMarker,
+        originalAsyncMarker: asyncMarker)
       ..fileOffset = offset
       ..fileEndOffset = endOffset;
   }