disable-anoncontent-highlighters.diff

exporting patch:
# HG changeset patch
# User Patrick Brosset <[email protected]>
# Date 1540390759 -7200
#      Wed Oct 24 16:19:19 2018 +0200
# Node ID 28252579eb8db33d857061e4db42a15e04a87e45
# Parent  079c7a062b23950449e9ce1ef809ff43026cc259
WIP pref to disable anoncontent highlighters

diff --git a/devtools/client/preferences/devtools-client.js b/devtools/client/preferences/devtools-client.js
--- a/devtools/client/preferences/devtools-client.js
+++ b/devtools/client/preferences/devtools-client.js
@@ -51,16 +51,19 @@ pref("devtools.inspector.showAllAnonymou
 // Enable the CSS shapes highlighter
 pref("devtools.inspector.shapesHighlighter.enabled", true);
 // Enable the Font Editor
 pref("devtools.inspector.fonteditor.enabled", true);
 // Enable the font highlight-on-hover feature
 pref("devtools.inspector.fonthighlighter.enabled", true);
 // Enable tracking of style changes and the Changes panel in the Inspector
 pref("devtools.inspector.changes.enabled", false);
+// Block all highlighters that require injecting content in the anonymous content
+// container of the nsCanvasFrame for the document.
+pref("devtools.inspector.blockAnonymousContentHighlighters", false);
 
 // Flexbox preferences
 // Enable the Flexbox highlighter and inspector panel in Nightly and DevEdition
 #if defined(NIGHTLY_BUILD) || defined(MOZ_DEV_EDITION)
 pref("devtools.inspector.flexboxHighlighter.enabled", true);
 pref("devtools.flexboxinspector.enabled", true);
 #else
 pref("devtools.inspector.flexboxHighlighter.enabled", false);
diff --git a/devtools/server/actors/highlighters.js b/devtools/server/actors/highlighters.js
--- a/devtools/server/actors/highlighters.js
+++ b/devtools/server/actors/highlighters.js
@@ -14,16 +14,20 @@ const { highlighterSpec, customHighlight
 
 loader.lazyRequireGetter(this, "isWindowIncluded", "devtools/shared/layout/utils", true);
 loader.lazyRequireGetter(this, "isXUL", "devtools/server/actors/highlighters/utils/markup", true);
 loader.lazyRequireGetter(this, "SimpleOutlineHighlighter", "devtools/server/actors/highlighters/simple-outline", true);
 loader.lazyRequireGetter(this, "BoxModelHighlighter", "devtools/server/actors/highlighters/box-model", true);
 
 const HIGHLIGHTER_PICKED_TIMER = 1000;
 const IS_OSX = Services.appinfo.OS === "Darwin";
+const BLOCK_ANONYMOUS_CONTENT_HIGHLIGHTERS_PREF =
+  "devtools.inspector.blockAnonymousContentHighlighters";
+const BLOCK_ANONYMOUS_CONTENT_HIGHLIGHTERS =
+  Services.prefs.getBoolPref(BLOCK_ANONYMOUS_CONTENT_HIGHLIGHTERS_PREF);
 
 /**
  * The registration mechanism for highlighters provide a quick way to
  * have modular highlighters, instead of a hard coded list.
  * It allow us to split highlighers in sub modules, and add them dynamically
  * using add-on (useful for 3rd party developers, or prototyping)
  *
  * Note that currently, highlighters added using add-ons, can only work on
@@ -114,29 +118,28 @@ exports.HighlighterActor = protocol.Acto
     return {
       actor: this.actorID,
     };
   },
 
   _createHighlighter: function() {
     this._isPreviousWindowXUL = isXUL(this._targetActor.window);
 
-    if (!this._isPreviousWindowXUL) {
-      this._highlighter = new BoxModelHighlighter(this._highlighterEnv,
-                                                  this._inspector);
+    if (!this._isPreviousWindowXUL && !BLOCK_ANONYMOUS_CONTENT_HIGHLIGHTERS) {
+      this._highlighter = new BoxModelHighlighter(this._highlighterEnv, this._inspector);
       this._highlighter.on("ready", this._highlighterReady);
       this._highlighter.on("hide", this._highlighterHidden);
     } else {
       this._highlighter = new SimpleOutlineHighlighter(this._highlighterEnv);
     }
   },
 
   _destroyHighlighter: function() {
     if (this._highlighter) {
-      if (!this._isPreviousWindowXUL) {
+      if (!this._isPreviousWindowXUL && !BLOCK_ANONYMOUS_CONTENT_HIGHLIGHTERS) {
         this._highlighter.off("ready", this._highlighterReady);
         this._highlighter.off("hide", this._highlighterHidden);
       }
       this._highlighter.destroy();
       this._highlighter = null;
     }
   },
 
@@ -447,26 +450,29 @@ exports.CustomHighlighterActor = protoco
       throw new Error(`${typeName} isn't a valid highlighter class (${list})`);
     }
 
     const constructor = require("./highlighters/" + modulePath)[typeName];
     // The assumption is that custom highlighters either need the canvasframe
     // container to append their elements and thus a non-XUL window or they have
     // to define a static XULSupported flag that indicates that the highlighter
     // supports XUL windows. Otherwise, bail out.
-    if (!isXUL(this._parent.targetActor.window) || constructor.XULSupported) {
+    if (!BLOCK_ANONYMOUS_CONTENT_HIGHLIGHTERS &&
+        (!isXUL(this._parent.targetActor.window) || constructor.XULSupported)) {
       this._highlighterEnv = new HighlighterEnvironment();
       this._highlighterEnv.initFromTargetActor(parent.targetActor);
       this._highlighter = new constructor(this._highlighterEnv);
       if (this._highlighter.on) {
         this._highlighter.on("highlighter-event", this._onHighlighterEvent.bind(this));
       }
+    } else if (!BLOCK_ANONYMOUS_CONTENT_HIGHLIGHTERS) {
+      throw new Error(`Custom ${typeName} highlighter cannot be created in a XUL window`);
     } else {
-      throw new Error("Custom " + typeName +
-        "highlighter cannot be created in a XUL window");
+      console.warn(`Because pref ${BLOCK_ANONYMOUS_CONTENT_HIGHLIGHTERS_PREF} is set ` +
+                   `to true, custom ${typeName} highlighter was not created`);
     }
   },
 
   get conn() {
     return this._parent && this._parent.conn;
   },
 
   destroy: function() {