DEV: Make image resize controls more resilient (#8867)

Commit aa24be1 made it possible to build data attributes from image's
Markdown and this changes ensure that the resize controls still work
when data attributes are present.

app/assets/javascripts/pretty-text/engines/discourse-markdown/resize-controls.js.es6

@@ -15,10 +15,15 @@ function buildToken(state, type, tag, klass, nesting) {
 
 function wrapImage(tokens, index, state, imgNumber) {
   const imgToken = tokens[index];
-  let selectedScale = imgToken.content
-    .split(",")
-    .pop()
-    .trim();
+  const sizePart = imgToken.content
+    .split("|")
+    .find(x => x.match(/\d{1,4}x\d{1,4}(,\s*\d{1,3}%)?/));
+  let selectedScale =
+    sizePart &&
+    sizePart
+      .split(",")
+      .pop()
+      .trim();
   tokens.splice(
     index,
     0,