[geary] (19 commits) ...Merge branch 'mjog/558-webkit-shared-process-redux' into 'mainline'

[Michael Gratton <mjog src gnome org>]

Summary of changes:

  d7af232... Revert "Revert "Merge branch 'mjog/558-webkit-shared-proces (*)
  1ba2bd0... Util.JS: Support converting between JSC.Value and GLib.Vari (*)
  ff565bc... Components.WebView: Convert to using messages for JS method (*)
  c813aa5... Components.WebView: Check for pass up exceptions when calli (*)
  db69807... GearyWebExtension: Add factory method for error user messag (*)
  6162785... GearyWebExtension: Add support for sending messages from JS (*)
  8945393... Util.Js: Improve JSC Value to GLib.Variant conversion (*)
  fb96676... Components.WebView: Convert to using messages for JS → clie (*)
  3655f48... Composer.WebView: Convert to using messages for JS → client (*)
  7b01462... Conversation.WebView: Convert to using messages for JS → cl (*)
  7950ce5... GearyWebExtension: Untangle extension and JS interaction a  (*)
  eba82a1... GearyWebExtension: Trivial code clean up (*)
  47b134a... Components.WebView: Remove now-unused message handler infra (*)
  92e842b... ConversationViewer.ConversationMessage: Fix valadoc warning (*)
  0609fbc... Util.JS: Remove now-unused code (*)
  1d80ed2... ComposerPageState: Use CSS for managing focus with composer (*)
  3f7c054... build: Bump WebKitGTK min version to include UserMessage su (*)
  4db6d01... client: Remove perf relnote, it's not really that noteworth (*)
  fac257a... Merge branch 'mjog/558-webkit-shared-process-redux' into 'm

(*) This commit already existed in another branch; no separate mail sent