Removed markdown-it-named-headers and unused string deps (#8994)

refs https://github.com/TryGhost/Ghost-Admin/pull/856

- moves `markdown-it-named-headers` functionality into our own app code without requiring the [`string.js`](http://stringjs.com) sub-dependency
- matches Ghost-Admin markdown-it code

core/server/utils/markdown-converter.js

@@ -7,16 +7,41 @@ var MarkdownIt  = require('markdown-it'),
     .use(require('markdown-it-footnote'))
     .use(require('markdown-it-lazy-headers'))
     .use(require('markdown-it-mark'))
-    .use(require('markdown-it-named-headers'), {
-        // match legacy Showdown IDs otherwise default is github style dasherized
-        slugify: function (inputString, usedHeaders) {
+    .use(function namedHeaders(md) {
+        // jscs:disable
+
+        // match legacy Showdown IDs
+        var slugify = function (inputString, usedHeaders) {
             var slug = inputString.replace(/[^\w]/g, '').toLowerCase();
             if (usedHeaders[slug]) {
                 usedHeaders[slug] += 1;
                 slug += usedHeaders[slug];
             }
             return slug;
-        }
+        };
+        var originalHeadingOpen = md.renderer.rules.heading_open;
+
+        // originally from https://github.com/leff/markdown-it-named-headers
+        // moved here to avoid pulling in http://stringjs.com dependency
+        md.renderer.rules.heading_open = function (tokens, idx, something, somethingelse, self) {
+            var used_headers = {};
+
+            tokens[idx].attrs = tokens[idx].attrs || [];
+
+            var title = tokens[idx + 1].children.reduce(function (acc, t) {
+                return acc + t.content;
+            }, '');
+
+            var slug = slugify(title, used_headers);
+            tokens[idx].attrs.push(['id', slug]);
+
+            if (originalHeadingOpen) {
+                return originalHeadingOpen.apply(this, arguments);
+            } else {
+                return self.renderToken.apply(self, arguments);
+            }
+        };
+        // jscs:enable
     });
 
 module.exports = {

package.json

@@ -67,7 +67,6 @@
     "markdown-it-footnote": "3.0.1",
     "markdown-it-lazy-headers": "0.1.3",
     "markdown-it-mark": "2.0.0",
-    "markdown-it-named-headers": "0.0.4",
     "mobiledoc-dom-renderer": "0.6.5",
     "moment": "2.18.1",
     "moment-timezone": "0.5.13",

yarn.lock

@@ -3311,12 +3311,6 @@ markdown-it-mark@2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/markdown-it-mark/-/markdown-it-mark-2.0.0.tgz#46a1aa947105aed8188978e0a016179e404f42c7"
 
-markdown-it-named-headers@0.0.4:
-  version "0.0.4"
-  resolved "https://registry.yarnpkg.com/markdown-it-named-headers/-/markdown-it-named-headers-0.0.4.tgz#82efc28324240a6b1e77b9aae501771d5f351c1f"
-  dependencies:
-    string "^3.0.1"
-
 markdown-it@8.4.0:
   version "8.4.0"
   resolved "https://registry.yarnpkg.com/markdown-it/-/markdown-it-8.4.0.tgz#e2400881bf171f7018ed1bd9da441dac8af6306d"
@@ -5040,10 +5034,6 @@ string-width@^1.0.1:
     is-fullwidth-code-point "^1.0.0"
     strip-ansi "^3.0.0"
 
-string@^3.0.1:
-  version "3.3.3"
-  resolved "https://registry.yarnpkg.com/string/-/string-3.3.3.tgz#5ea211cd92d228e184294990a6cc97b366a77cb0"
-
 string_decoder@~0.10.x:
   version "0.10.31"
   resolved "https://registry.yarnpkg.com/string_decoder/-/string_decoder-0.10.31.tgz#62e203bc41766c6c28c9fc84301dab1c5310fa94"