Redefining a function panics with binding already exists

[dvtkrlbs]

Redefining a function in repl panics with binding already exists error

To Reproduce
Steps to reproduce the issue, or JavaScript code that causes this failure.
cargo run
function x() {} enter
function x() { return 3; } enter panics

Expected behavior
It should override the previous binding

Backtrace

thread 'main' panicked at 'Binding already exists!', boa/src/environment/global_environment_record.rs:108:13
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /Users/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /Users/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:78
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:59
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1076
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1537
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:62
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:198
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:217
  10: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:526
  11: std::panicking::begin_panic
  12: <boa::environment::global_environment_record::GlobalEnvironmentRecord as boa::environment::environment_record_trait::EnvironmentRecordTrait>::create_mutable_binding
             at boa/src/environment/global_environment_record.rs:108
  13: boa::environment::lexical_environment::LexicalEnvironment::create_mutable_binding
             at /Users/dvtkrlbs/.cargo/registry/src/github.com-1ecc6299db9ec823/hashbrown-0.8.2/src/raw/mod.rs:1822
  14: boa::exec::declaration::<impl boa::exec::Executable for boa::syntax::ast::node::declaration::FunctionDecl>::run
             at boa/src/exec/declaration/mod.rs:24
  15: <boa::syntax::ast::node::Node as boa::exec::Executable>::run
             at boa/src/exec/mod.rs:389
  16: boa::exec::statement_list::<impl boa::exec::Executable for boa::syntax::ast::node::statement_list::StatementList>::run
             at boa/src/exec/statement_list.rs:15
  17: boa::forward_val
             at boa/src/lib.rs:89
  18: boa::main
             at boa_cli/src/main.rs:190
  19: std::rt::lang_start::{{closure}}
             at /Users/dvtkrlbs/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/src/rust/src/libstd/rt.rs:67
  20: std::rt::lang_start_internal::{{closure}}
             at src/libstd/rt.rs:52
  21: std::panicking::try::do_call
             at src/libstd/panicking.rs:348
  22: std::panicking::try
             at src/libstd/panicking.rs:325
  23: std::panic::catch_unwind
             at src/libstd/panic.rs:394
  24: std::rt::lang_start_internal
             at src/libstd/rt.rs:51
  25: std::rt::lang_start
             at /Users/dvtkrlbs/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/src/rust/src/libstd/rt.rs:67
  26: main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.