[gjs] (9 commits) ...Merge branch 'memleak-fixes' into 'master'

[Philip Chimento <pchimento src gnome org>]

Summary of changes:

  926be39... gtype: delete heap wrappers on gtype removal
  4b6b096... gtype: track weak pointers using unique_ptr
  d174bb8... gtype: reuse heap wrapper from cached ones
  57e72b9... engine: delete context if hosted code can't be defined
  08bd2d3... importer: use gjs_string_from_utf8 to convert strings
  0b06014... gtype: use Atomized string for static ones
  8ec02d1... importer: rename file name as parse_name
  e0f0707... native: rename file name as parse_name
  72f2e94... Merge branch 'memleak-fixes' into 'master'