Save transient state

Change-Id: I1c2405b1237b6017a92b789452671938e0c25705
Reviewed-on: https://dart-review.googlesource.com/c/88448
Reviewed-by: Dmitry Stefantsov <[email protected]>
Commit-Queue: Peter von der Ahé <[email protected]>

Author: peter-ahe-google

pkg/front_end/lib/src/fasta/kernel/class_hierarchy_builder.dart

@@ -156,6 +156,8 @@ class ClassHierarchyBuilder {
   }
 
   void add(KernelClassBuilder cls) {
+    assert(!hasNoSuchMethod);
+    assert(abstractMemberCount == 0);
     if (cls.isPatch) {
       // TODO(ahe): What about patch classes. Have we injected patched members
       // into the class-builder's scope?
@@ -390,7 +392,13 @@ class ClassHierarchyBuilder {
     if (declaration is KernelClassBuilder) {
       ClassHierarchyNode node = nodes[declaration];
       if (node == null) {
+        bool savedHasNoSuchMethod = hasNoSuchMethod;
+        hasNoSuchMethod = false;
+        int savedAbstractMemberCount = abstractMemberCount;
+        abstractMemberCount = 0;
         add(declaration);
+        hasNoSuchMethod = savedHasNoSuchMethod;
+        abstractMemberCount = savedAbstractMemberCount;
         node = nodes[declaration];
       }
       return node;