Make non-Module generators only context allocate parameters.

src/ast/scopes.h

Index: src/ast/scopes.h
diff --git a/src/ast/scopes.h b/src/ast/scopes.h
index ba7aa020b6c0f44c40cf5584089c7c2feaec1775..a4f76b6037892ee5ac7292b70f6cffd7fc5080d6 100644
--- a/src/ast/scopes.h
+++ b/src/ast/scopes.h
@@ -323,6 +323,13 @@ class V8_EXPORT_PRIVATE Scope : public NON_EXPORTED_BASE(ZoneObject) {
   bool has_forced_context_allocation() const {
     return force_context_allocation_;
   }
+  void ForceContextAllocationForParameters() {
+    DCHECK(!already_resolved_);
+    force_context_allocation_for_parameters_ = true;
+  }
+  bool has_forced_context_allocation_for_parameters() const {
+    return force_context_allocation_for_parameters_;
+  }
 
   // ---------------------------------------------------------------------------
   // Predicates.
@@ -574,6 +581,7 @@ class V8_EXPORT_PRIVATE Scope : public NON_EXPORTED_BASE(ZoneObject) {
   // True if one of the inner scopes or the scope itself calls eval.
   bool inner_scope_calls_eval_ : 1;
   bool force_context_allocation_ : 1;
+  bool force_context_allocation_for_parameters_ : 1;
 
   // True if it holds 'var' declarations.
   bool is_declaration_scope_ : 1;