Don't assume `document.documentElement` is non-null (#3857)

* Fix uBlockOrigin/uBlock-issues#1756

This PR fixes uBlockOrigin/uBlock-issues#1756.

* fix dom-inspector.js

* more explicit if statements

* these changes should also be safe

assets/resources/scriptlets.js

@@ -788,7 +788,7 @@
         rmattr();
         if ( /\bstay\b/.test(behavior) === false ) { return; }
         const observer = new MutationObserver(mutationHandler);
-        observer.observe(document.documentElement, {
+        observer.observe(document, {
             attributes: true,
             attributeFilter: tokens,
             childList: true,
@@ -847,7 +847,7 @@
         rmclass();
         if ( /\bstay\b/.test(behavior) === false ) { return; }
         const observer = new MutationObserver(mutationHandler);
-        observer.observe(document.documentElement, {
+        observer.observe(document, {
             attributes: true,
             attributeFilter: [ 'class' ],
             childList: true,
@@ -1555,7 +1555,7 @@
         asyncTimer = window.requestAnimationFrame(cleanVideo);
     };
     var observer = new MutationObserver(cleanVideoAsync);
-    observer.observe(document.documentElement, { childList: true, subtree: true });
+    observer.observe(document, { childList: true, subtree: true });
 })();
 
 

src/js/contentscript.js

@@ -393,7 +393,7 @@ vAPI.SafeAnimationFrame = class {
     const startMutationObserver = function() {
         if ( domLayoutObserver !== undefined ) { return; }
         domLayoutObserver = new MutationObserver(observerHandler);
-        domLayoutObserver.observe(document.documentElement, {
+        domLayoutObserver.observe(document, {
             //attributeFilter: [ 'class', 'id' ],
             //attributes: true,
             childList: true,
@@ -469,7 +469,7 @@ vAPI.injectScriptlet = function(doc, text) {
     try {
         script = doc.createElement('script');
         script.appendChild(doc.createTextNode(text));
-        (doc.head || doc.documentElement).appendChild(script);
+        (doc.head || doc.documentElement || doc).appendChild(script);
     } catch (ex) {
     }
     if ( script ) {
@@ -1171,10 +1171,14 @@ vAPI.DOMFilterer = class {
             //   Look-up safe-only selectors to mitigate probability of
             //   html/body elements of erroneously being targeted.
             const ids = [], classes = [];
+            if (document.documentElement !== null) {
                 idFromNode(document.documentElement, ids);
-            idFromNode(document.body, ids);
                 classesFromNode(document.documentElement, classes);
+            }
+            if (document.body !== null) {
+                idFromNode(document.body, ids);
                 classesFromNode(document.body, classes);
+            }
             if ( ids.length !== 0 || classes.length !== 0 ) {
                 messaging.send('contentscript', {
                     what: 'retrieveGenericCosmeticSelectors',

src/js/scriptlets/dom-inspector.js

@@ -247,7 +247,7 @@ const domLayout = (function() {
     const getLayoutData = function() {
         var layout = [];
         var stack = [];
-        var node = document.documentElement;
+        var node = document;
         var domNode;
         var lvl = 0;
 
@@ -264,6 +264,7 @@ const domLayout = (function() {
                 continue;
             }
             // sibling
+            if (node instanceof Element) {
                 if ( node.nextElementSibling === null ) {
                     do {
                         node = stack.pop();
@@ -274,6 +275,7 @@ const domLayout = (function() {
                 }
                 node = node.nextElementSibling;
             }
+        }
 
         return layout;
     };
@@ -547,7 +549,9 @@ const cosmeticFilterMapper = (function() {
 
     const reset = function() {
         roRedNodes.clear();
+        if (document.documentElement !== null) {
             incremental(document.documentElement);
+        }
     };
 
     const shutdown = function() {
@@ -812,7 +816,7 @@ const shutdown = function() {
     domLayout.shutdown();
     vAPI.MessagingConnection.disconnectFrom(loggerConnectionId);
     window.removeEventListener('scroll', onScrolled, true);
-    document.documentElement.removeChild(pickerRoot);
+    pickerRoot.remove();
     pickerRoot = svgRoot = null;
 };
 
@@ -977,7 +981,7 @@ pickerRoot.style.cssText = [
 ].join(' !important;\n');
 
 pickerRoot.addEventListener('load', ev => { bootstrap(ev); });
-document.documentElement.appendChild(pickerRoot);
+(document.documentElement || document).appendChild(pickerRoot);
 
 /******************************************************************************/