Eliminate all but one top-level class per library.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 3d36a76859cb210e9648811c0b039a22e6865e7b..9000362f5e7b99c5442567c42fc69139171862e8 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -1716,8 +1716,8 @@ class TypeArguments : public Object {
 class PatchClass : public Object {
  public:
   RawClass* patched_class() const { return raw_ptr()->patched_class_; }
-  RawClass* source_class() const { return raw_ptr()->source_class_; }
-  RawScript* Script() const;
+  RawClass* origin_class() const { return raw_ptr()->origin_class_; }
+  RawScript* script() const { return raw_ptr()->script_; }
 
   static intptr_t InstanceSize() {
     return RoundedAllocationSize(sizeof(RawPatchClass));
@@ -1728,11 +1728,15 @@ class PatchClass : public Object {
   }
 
   static RawPatchClass* New(const Class& patched_class,
-                            const Class& source_class);
+                            const Class& origin_class);
+
+  static RawPatchClass* New(const Class& patched_class,
+                            const Script& source);
 
  private:
   void set_patched_class(const Class& value) const;
-  void set_source_class(const Class& value) const;
+  void set_origin_class(const Class& value) const;
+  void set_script(const Script& value) const;
 
   static RawPatchClass* New();
 
@@ -2136,6 +2140,7 @@ class Function : public Object {
   RawClass* Owner() const;
   RawClass* origin() const;
   RawScript* script() const;
+  RawObject* RawOwner() const { return raw_ptr()->owner_; }
 
   RawJSRegExp* regexp() const;
   intptr_t string_specialization_cid() const;
@@ -2863,6 +2868,9 @@ class Field : public Object {
   bool is_reflectable() const {
     return ReflectableBit::decode(raw_ptr()->kind_bits_);
   }
+  void set_is_reflectable(bool value) const {
+    set_kind_bits(ReflectableBit::update(value, raw_ptr()->kind_bits_));
+  }
   bool is_double_initialized() const {
     return DoubleInitializedBit::decode(raw_ptr()->kind_bits_);
   }
@@ -2883,6 +2891,8 @@ class Field : public Object {
 
   RawClass* owner() const;
   RawClass* origin() const;  // Either mixin class, or same as owner().
+  RawScript* script() const;
+  RawObject* RawOwner() const { return raw_ptr()->owner_; }
 
   RawAbstractType* type() const  { return raw_ptr()->type_; }
   // Used by class finalizer, otherwise initialized in constructor.
@@ -2901,6 +2911,12 @@ class Field : public Object {
                        const AbstractType& type,
                        intptr_t token_pos);
 
+  static RawField* NewTopLevel(const String& name,
+                               bool is_final,
+                               bool is_const,
+                               const Object& owner,
+                               intptr_t token_pos);
+
   // Allocate new field object, clone values from this field. The
   // owner of the clone is new_owner.
   RawField* Clone(const Class& new_owner) const;
@@ -3089,9 +3105,6 @@ class Field : public Object {
   void set_is_const(bool value) const {
     set_kind_bits(ConstBit::update(value, raw_ptr()->kind_bits_));
   }
-  void set_is_reflectable(bool value) const {
-    set_kind_bits(ReflectableBit::update(value, raw_ptr()->kind_bits_));
-  }
   void set_owner(const Object& value) const {
     StorePointer(&raw_ptr()->owner_, value.raw());
   }
@@ -3317,6 +3330,8 @@ class DictionaryIterator : public ValueObject {
 class ClassDictionaryIterator : public DictionaryIterator {
  public:
   enum IterationKind {
+    // TODO(hausner): fix call sites that use kIteratePrivate. There is only
+    // one top-level class per library left, not an array to iterate over.
     kIteratePrivate,
     kNoIteratePrivate
   };
@@ -3324,7 +3339,9 @@ class ClassDictionaryIterator : public DictionaryIterator {
   ClassDictionaryIterator(const Library& library,
                           IterationKind kind = kNoIteratePrivate);
 
-  bool HasNext() const { return (next_ix_ < size_) || (anon_ix_ < anon_size_); }
+  bool HasNext() const {
+      return (next_ix_ < size_) || !toplevel_class_.IsNull();
+  }
 
   // Returns a non-null raw class.
   RawClass* GetNextClass();
@@ -3332,9 +3349,7 @@ class ClassDictionaryIterator : public DictionaryIterator {
  private:
   void MoveToNextClass();
 
-  const Array& anon_array_;
-  const int anon_size_;  // Number of anonymous classes to iterate over.
-  int anon_ix_;  // Index of next anonymous class.
+  Class& toplevel_class_;
 
   DISALLOW_COPY_AND_ASSIGN(ClassDictionaryIterator);
 };
@@ -3430,17 +3445,19 @@ class Library : public Object {
   void AddExport(const Namespace& ns) const;
 
   void AddClassMetadata(const Class& cls,
-                        const Class& toplevel_class,
+                        const Object& tl_owner,
                         intptr_t token_pos) const;
   void AddFieldMetadata(const Field& field, intptr_t token_pos) const;
   void AddFunctionMetadata(const Function& func, intptr_t token_pos) const;
-  void AddLibraryMetadata(const Class& cls, intptr_t token_pos) const;
+  void AddLibraryMetadata(const Object& tl_owner, intptr_t token_pos) const;
   void AddTypeParameterMetadata(const TypeParameter& param,
                                 intptr_t token_pos) const;
   RawObject* GetMetadata(const Object& obj) const;
 
-  intptr_t num_anonymous_classes() const { return raw_ptr()->num_anonymous_; }
-  RawArray* anonymous_classes() const { return raw_ptr()->anonymous_classes_; }
+  RawClass* toplevel_class() const {
+    return raw_ptr()->toplevel_class_;
+  }
+  void set_toplevel_class(const Class& value) const;
 
   RawGrowableObjectArray* patch_classes() const {
     return raw_ptr()->patch_classes_;
@@ -3588,7 +3605,7 @@ class Library : public Object {
 
   RawString* MakeMetadataName(const Object& obj) const;
   RawField* GetMetadataField(const String& metaname) const;
-  void AddMetadata(const Class& cls,
+  void AddMetadata(const Object& owner,
                    const String& name,
                    intptr_t token_pos) const;
 
@@ -3611,7 +3628,7 @@ class Namespace : public Object {
   RawArray* show_names() const { return raw_ptr()->show_names_; }
   RawArray* hide_names() const { return raw_ptr()->hide_names_; }
 
-  void AddMetadata(intptr_t token_pos, const Class& owner_class);
+  void AddMetadata(const Object& owner, intptr_t token_pos);
   RawObject* GetMetadata() const;
 
   static intptr_t InstanceSize() {