PreParser: track variable declarations and parameters

src/parsing/preparser.cc

Index: src/parsing/preparser.cc
diff --git a/src/parsing/preparser.cc b/src/parsing/preparser.cc
index 306fb264d1c17116d189d87aefedbcc65a6a8dbf..d53551430a2391936fa800debae6aa4c7f435b98 100644
--- a/src/parsing/preparser.cc
+++ b/src/parsing/preparser.cc
@@ -296,7 +296,10 @@ void PreParser::DeclareAndInitializeVariables(
        var + initializer -> RemoveUnresolved followed by NewUnresolved
        let / const + initializer -> RemoveUnresolved
     */
-
+    Scope* scope = declaration_descriptor->hoist_scope;
+    if (scope == nullptr) {
+      scope = this->scope();
+    }
     if (declaration->initializer.IsEmpty() ||
         (declaration_descriptor->mode == VariableMode::LET ||
          declaration_descriptor->mode == VariableMode::CONST)) {
@@ -304,6 +307,9 @@ void PreParser::DeclareAndInitializeVariables(
         declaration_descriptor->scope->RemoveUnresolved(identifier);
       }
     }
+    for (auto identifier : *(declaration->pattern.identifiers_)) {
+      scope->DeclareVariableName(identifier, declaration_descriptor->mode);
+    }
   }
 }