Chain ScopeInfos together

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index b4fec8ee7e35495d9622a555cec82f8396cfd821..6d278c2f2d6c325208aab9cf7e74e170ce5ce8dd 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -4391,6 +4391,12 @@ class ScopeInfo : public FixedArray {
 
   FunctionKind function_kind();
 
+  // Returns true if this ScopeInfo is linked to a outer ScopeInfo.
+  bool HasOuterScopeInfo();
+
+  // Return the outer ScopeInfo if present.
+  ScopeInfo* OuterScopeInfo();
+
   static Handle<ScopeInfo> Create(Isolate* isolate, Zone* zone, Scope* scope);
   static Handle<ScopeInfo> CreateGlobalThisBinding(Isolate* isolate);
 
@@ -4464,6 +4470,8 @@ class ScopeInfo : public FixedArray {
   //    information about the function variable. It always occupies two array
   //    slots:  a. The name of the function variable.
   //            b. The context or stack slot index for the variable.
+  // 8. OuterScopeInfoEntryIndex:
+  //    The outer scope's ScopeInfo or the hole if there's none.
   int ParameterEntriesIndex();
   int StackLocalFirstSlotIndex();
   int StackLocalEntriesIndex();
@@ -4473,6 +4481,7 @@ class ScopeInfo : public FixedArray {
   int ContextGlobalInfoEntriesIndex();
   int ReceiverEntryIndex();
   int FunctionNameEntryIndex();
+  int OuterScopeInfoEntryIndex();
 
   int Lookup(Handle<String> name, int start, int end, VariableMode* mode,
              VariableLocation* location, InitializationFlag* init_flag,
@@ -4506,6 +4515,8 @@ class ScopeInfo : public FixedArray {
       : public BitField<bool, AsmFunctionField::kNext, 1> {};
   class FunctionKindField
       : public BitField<FunctionKind, HasSimpleParametersField::kNext, 9> {};
+  class HasOuterScopeInfoField
+      : public BitField<bool, FunctionKindField::kNext, 1> {};
 
   // Properties of variables.
   class VariableModeField : public BitField<VariableMode, 0, 3> {};