Resynthesize mixins from Kernel.

pkg/kernel/lib/binary/ast_from_binary.dart

Index: pkg/kernel/lib/binary/ast_from_binary.dart
diff --git a/pkg/kernel/lib/binary/ast_from_binary.dart b/pkg/kernel/lib/binary/ast_from_binary.dart
index 3d556eb82bc75aead025532c4a3c49a00492c0ff..1e7f8762dad21bfac4914cee9da505ba20a35bdc 100644
--- a/pkg/kernel/lib/binary/ast_from_binary.dart
+++ b/pkg/kernel/lib/binary/ast_from_binary.dart
@@ -463,7 +463,8 @@ class BinaryBuilder {
     node.fileEndOffset = readOffset();
     int flags = readByte();
     node.isAbstract = flags & 0x1 != 0;
-    int levelIndex = (flags >> 1) & 0x3;
+    node.isSyntheticMixinImplementation = flags & 0x2 != 0;
+    int levelIndex = (flags >> 2) & 0x3;

[Siggi Cherem (dart-lang), 2017/07/21 16:46:43]

just to double check - in C++ they don't need to deserialize the flags? (is that
why there is no corresponding change in the c++ side?)

[scheglov, 2017/07/21 16:49:37]

Correct. In C++ the code reads the byte and uses just one bit.
      case kIsAbstract:
        is_abstract_ = builder_->ReadBool();  // read is_abstract.
        if (++next_read_ == field) return;

     var level = ClassLevel.values[levelIndex + 1];
     if (level.index >= node.level.index) {
       node.level = level;