LibJS: Expose various offsets for GetGlobal JIT fast path

Userland/Libraries/LibJS/Bytecode/Executable.h

@@ -34,6 +34,8 @@ struct PropertyLookupCache {
 };
 
 struct GlobalVariableCache : public PropertyLookupCache {
+    static FlatPtr environment_serial_number_offset() { return OFFSET_OF(GlobalVariableCache, environment_serial_number); }
+
     u64 environment_serial_number { 0 };
 };
 

Userland/Libraries/LibJS/Runtime/DeclarativeEnvironment.h

@@ -71,6 +71,7 @@ public:
     [[nodiscard]] u64 environment_serial_number() const { return m_environment_serial_number; }
 
     static FlatPtr bindings_offset() { return OFFSET_OF(DeclarativeEnvironment, m_bindings); }
+    static FlatPtr environment_serial_number_offset() { return OFFSET_OF(DeclarativeEnvironment, m_environment_serial_number); }
 
 private:
     ThrowCompletionOr<Value> get_binding_value_direct(VM&, Binding&, bool strict);

Userland/Libraries/LibJS/Runtime/ExecutionContext.h

@@ -30,6 +30,7 @@ struct ExecutionContext {
 
     void visit_edges(Cell::Visitor&);
 
+    static FlatPtr realm_offset() { return OFFSET_OF(ExecutionContext, realm); }
     static FlatPtr lexical_environment_offset() { return OFFSET_OF(ExecutionContext, lexical_environment); }
 
 private:

Userland/Libraries/LibJS/Runtime/GlobalEnvironment.h

@@ -37,6 +37,9 @@ public:
     ThrowCompletionOr<void> create_global_var_binding(DeprecatedFlyString const& name, bool can_be_deleted);
     ThrowCompletionOr<void> create_global_function_binding(DeprecatedFlyString const& name, Value, bool can_be_deleted);
 
+    static FlatPtr object_record_offset() { return OFFSET_OF(GlobalEnvironment, m_object_record); }
+    static FlatPtr declarative_record_offset() { return OFFSET_OF(GlobalEnvironment, m_declarative_record); }
+
 private:
     GlobalEnvironment(Object&, Object& this_value);
 

Userland/Libraries/LibJS/Runtime/ObjectEnvironment.h

@@ -41,6 +41,8 @@ public:
     // [[IsWithEnvironment]], Indicates whether this Environment Record is created for a with statement.
     bool is_with_environment() const { return m_with_environment; }
 
+    static FlatPtr binding_object_offset() { return OFFSET_OF(ObjectEnvironment, m_binding_object); }
+
 private:
     ObjectEnvironment(Object& binding_object, IsWithEnvironment, Environment* outer_environment);
 

Userland/Libraries/LibJS/Runtime/Realm.h

@@ -48,6 +48,8 @@ public:
     HostDefined* host_defined() { return m_host_defined; }
     void set_host_defined(OwnPtr<HostDefined> host_defined) { m_host_defined = move(host_defined); }
 
+    static FlatPtr global_environment_offset() { return OFFSET_OF(Realm, m_global_environment); }
+
 private:
     Realm() = default;