FEATURE: used strict sanitizer by default

This amends it so sanitize always uses the most strict sanitizer
by default, if it needs to be "widened" to use more options then
you need to pass it more options.

app/assets/javascripts/discourse/lib/text.js.es6

@@ -33,8 +33,8 @@ export function cookAsync(text, options) {
 }
 
 
-export function sanitize(text) {
-  return textSanitize(text, new WhiteLister(getOpts()));
+export function sanitize(text, options) {
+  return textSanitize(text, new WhiteLister(options));
 }
 
 function emojiOptions() {

app/assets/javascripts/pretty-text/white-lister.js.es6

@@ -14,12 +14,18 @@ function concatUniq(src, elems) {
 
 export default class WhiteLister {
   constructor(options) {
+    options = options || {
+      features: {
+        default: true
+      }
+    };
+
     options.features.default = true;
 
     this._featureKeys = Object.keys(options.features).filter(f => options.features[f]);
     this._key = this._featureKeys.join(':');
     this._features = options.features;
-    this._options = options||{};
+    this._options = {};
   }
 
   getCustom() {