Support for modular mixin resolution.

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 8c940f69fe5586c80a9aab09cc9354c5f8db56a9..0ca2f6074d92f10566fe8414692cb8963e6e9cdc 100644
--- a/pkg/kernel/lib/binary/ast_from_binary.dart
+++ b/pkg/kernel/lib/binary/ast_from_binary.dart
@@ -324,9 +324,8 @@ class BinaryBuilder {
     node.fileOffset = readOffset();
     int flags = readByte();
     node.isAbstract = flags & 0x1 != 0;
-    node.level = _currentLibrary.isExternal
-        ? (flags & 0x2 != 0) ? ClassLevel.Type : ClassLevel.Hierarchy
-        : ClassLevel.Body;
+    int levelIndex = (flags >> 1) & 0x3;
+    node.level = ClassLevel.values[levelIndex + 1];
     node.name = readStringOrNullIfEmpty();
     node.fileUri = readUriReference();
     node.annotations = readAnnotationList(node);
@@ -351,9 +350,8 @@ class BinaryBuilder {
     node.fileOffset = readOffset();
     int flags = readByte();
     node.isAbstract = flags & 0x1 != 0;
-    node.level = _currentLibrary.isExternal
-        ? (flags & 0x2 != 0) ? ClassLevel.Type : ClassLevel.Hierarchy
-        : ClassLevel.Body;
+    int levelIndex = (flags >> 1) & 0x3;
+    node.level = ClassLevel.values[levelIndex];
     node.name = readStringOrNullIfEmpty();
     node.fileUri = readUriReference();
     node.annotations = readAnnotationList(node);