[strong] Stricter check for referring to other classes inside methods.

src/variables.h

Index: src/variables.h
diff --git a/src/variables.h b/src/variables.h
index de7f39045af934d8a7d13320f58cbc8cb88588a2..739090a884c35f5d097517ccb4fc8a3dd13938e2 100644
--- a/src/variables.h
+++ b/src/variables.h
@@ -16,6 +16,8 @@ namespace internal {
 // they are maintained by scopes, and referred to from VariableProxies and Slots
 // after binding and variable allocation.
 
+class ClassVariable;
+
 class Variable: public ZoneObject {
  public:
   enum Kind { NORMAL, FUNCTION, CLASS, THIS, NEW_TARGET, ARGUMENTS };
@@ -51,6 +53,8 @@ class Variable: public ZoneObject {
            InitializationFlag initialization_flag,
            MaybeAssignedFlag maybe_assigned_flag = kNotAssigned);
 
+  virtual ~Variable() {}
+
   // Printing support
   static const char* Mode2String(VariableMode mode);
 
@@ -102,6 +106,11 @@ class Variable: public ZoneObject {
   bool is_new_target() const { return kind_ == NEW_TARGET; }
   bool is_arguments() const { return kind_ == ARGUMENTS; }
 
+  ClassVariable* AsClassVariable() {
+    DCHECK(is_class());
+    return reinterpret_cast<ClassVariable*>(this);
+  }
+
   // True if the variable is named eval and not known to be shadowed.
   bool is_possibly_eval(Isolate* isolate) const {
     return IsVariable(isolate->factory()->eval_string());
@@ -175,7 +184,33 @@ class Variable: public ZoneObject {
   MaybeAssignedFlag maybe_assigned_;
 };
 
+class ClassVariable : public Variable {
+ public:
+  ClassVariable(Scope* scope, const AstRawString* name, VariableMode mode,
+                Kind kind, InitializationFlag initialization_flag,
+                MaybeAssignedFlag maybe_assigned_flag = kNotAssigned,
+                int declaration_group_start = -1)
+      : Variable(scope, name, mode, kind, initialization_flag,
+                 maybe_assigned_flag),
+        declaration_group_start_(declaration_group_start),
+        corresponding_outer_class_variable_(nullptr) {}
+
+  int declaration_group_start() const { return declaration_group_start_; }
+
+  ClassVariable* corresponding_outer_class_variable() const {
+    return corresponding_outer_class_variable_;
+  }
+  void set_corresponding_outer_class_variable(ClassVariable* var) {
+    corresponding_outer_class_variable_ = var;
+  }
 
+ private:
+  // For classes we keep track of consecutive groups of delcarations. They are
+  // needed for strong mode scoping checks. TODO(marja, rossberg): Implement
+  // checks for functions too.
+  int declaration_group_start_;
+  ClassVariable* corresponding_outer_class_variable_;
+};
 } }  // namespace v8::internal
 
 #endif  // V8_VARIABLES_H_