LibJS/Bytecode: Always return false on attempt to delete local variable

Since it is not possible for delete operator to return true when it is
applied to local variable, DeleteVariable can safely always return
false for locals.

This also fixes operators/delete-local-variable.js in test-js.

Userland/Libraries/LibJS/Bytecode/Generator.cpp

@@ -298,7 +298,10 @@ CodeGenerationErrorOr<void> Generator::emit_delete_reference(JS::ASTNode const&
 {
     if (is<Identifier>(node)) {
         auto& identifier = static_cast<Identifier const&>(node);
-        emit<Bytecode::Op::DeleteVariable>(intern_identifier(identifier.string()));
+        if (identifier.is_local())
+            emit<Bytecode::Op::LoadImmediate>(Value(false));
+        else
+            emit<Bytecode::Op::DeleteVariable>(intern_identifier(identifier.string()));
         return {};
     }