enable lazy-loading of gitgraph.js (#9036)

- moved gitgraph.js to web_src and made it importable and es6-compatible
- created new webpack chunk for gitgraph
- enabled CSS loader in webpack
- enabled async/await syntax via regenerator-runtime
- added script to ensure webpack chunks are loaded correctly
- disable terser's comment extraction to prevent .LICENCE files

gitgraph.js has many issues:

1. it is incompatible with ES6 because of strict-mode violations
1. it does not export anything
1. it's css has weird styles like for `body`
1. it is not available on npm

I fixed points 1-3 in our version so it's now loadable in webpack. We should eventually consider alternatives.

3 files changed, 1 insertions, 11 deletions

diff --git a/templates/base/footer.tmpl b/templates/base/footer.tmpl
index 93cf941673..0c07fb6e70 100644
--- a/templates/base/footer.tmpl
+++ b/templates/base/footer.tmpl
@@ -23,10 +23,6 @@
 		CodeMirror.modeURL =  "{{StaticUrlPrefix}}/vendor/plugins/codemirror/mode/%N/%N.js";
 	</script>
 {{end}}
-{{if .RequireGitGraph}}
-	<!-- graph -->
-	<script src="{{StaticUrlPrefix}}/vendor/plugins/gitgraph/gitgraph.js"></script>
-{{end}}
 
 <!-- Third-party libraries -->
 {{if .RequireHighlightJS}}
diff --git a/templates/base/head.tmpl b/templates/base/head.tmpl
index c0686ca93e..32251f84ae 100644
--- a/templates/base/head.tmpl
+++ b/templates/base/head.tmpl
@@ -87,11 +87,6 @@
 	<link rel="stylesheet" href="{{StaticUrlPrefix}}/vendor/plugins/simplemde/simplemde.min.css">
 {{end}}
 
-{{if .RequireGitGraph}}
-	<!-- graph -->
-	<link rel="stylesheet" href="{{StaticUrlPrefix}}/vendor/plugins/gitgraph/gitgraph.css">
-{{end}}
-
 {{if .RequireTribute}}
 	<link rel="stylesheet" href="{{StaticUrlPrefix}}/vendor/plugins/tribute/tribute.css">
 {{end}}
diff --git a/templates/pwa/serviceworker_js.tmpl b/templates/pwa/serviceworker_js.tmpl
index 672e504ff3..59f3be4131 100644
--- a/templates/pwa/serviceworker_js.tmpl
+++ b/templates/pwa/serviceworker_js.tmpl
@@ -6,9 +6,9 @@ var urlsToCache = [
   '{{StaticUrlPrefix}}/vendor/plugins/jquery-migrate/jquery-migrate.min.js?v=3.0.1',
   '{{StaticUrlPrefix}}/vendor/plugins/semantic/semantic.min.js',
   '{{StaticUrlPrefix}}/js/index.js?v={{MD5 AppVer}}',
+  '{{StaticUrlPrefix}}/js/gitgraph.js?v={{MD5 AppVer}}',
   '{{StaticUrlPrefix}}/js/semantic.dropdown.custom.js?v={{MD5 AppVer}}',
   '{{StaticUrlPrefix}}/vendor/plugins/clipboard/clipboard.min.js',
-  '{{StaticUrlPrefix}}/vendor/plugins/gitgraph/gitgraph.js',
   '{{StaticUrlPrefix}}/vendor/plugins/vue/vue.min.js',
   '{{StaticUrlPrefix}}/vendor/plugins/emojify/emojify.custom.js',
   '{{StaticUrlPrefix}}/vendor/plugins/cssrelpreload/loadCSS.min.js',
@@ -25,7 +25,6 @@ var urlsToCache = [
   '{{StaticUrlPrefix}}/vendor/assets/font-awesome/css/font-awesome.min.css',
   '{{StaticUrlPrefix}}/vendor/assets/octicons/octicons.min.css',
   '{{StaticUrlPrefix}}/vendor/plugins/simplemde/simplemde.min.css',
-  '{{StaticUrlPrefix}}/vendor/plugins/gitgraph/gitgraph.css',
   '{{StaticUrlPrefix}}/vendor/plugins/tribute/tribute.css',
   '{{StaticUrlPrefix}}/vendor/plugins/semantic/semantic.min.css',
   '{{StaticUrlPrefix}}/css/index.css?v={{MD5 AppVer}}',