cssOrigin.patch

diff -r b615bfdf4897 -r a7309348a8e9 lib/cssInjection.js
--- a/lib/cssInjection.js	Thu Sep 14 20:54:34 2017 -0400
+++ b/lib/cssInjection.js	Fri Sep 15 11:07:11 2017 -0400
@@ -26,38 +26,20 @@
 const {port} = require("messaging");
 const devtools = require("devtools");
 
-let userStylesheetsSupported = true;
-
 function hideElements(tabId, frameId, selectors)
 {
-  let code = selectors.join(", ") + "{display: none !important;}";
-
-  try
-  {
-    chrome.tabs.insertCSS(tabId,
-      {
-        code,
-        cssOrigin: "user",
-        frameId,
-        matchAboutBlank: true,
-        runAt: "document_start"
-      }
-    );
-    return true;
-  }
-  catch (error)
-  {
-    if (/\bError processing cssOrigin\b/.test(error.message) == -1)
-      throw error;
-
-    userStylesheetsSupported = false;
-    return false;
-  }
+  chrome.tabs.insertCSS(tabId, {
+    selectors.join(", ") + "{display: none !important;}",
+    cssOrigin: "user",
+    frameId,
+    matchAboutBlank: true,
+    runAt: "document_start"
+  });
 }
 
 port.on("elemhide.getSelectors", (msg, sender) =>
 {
-  let selectors;
+  let selectors = null;
   let trace = devtools && devtools.hasPanel(sender.page);
 
   if (!checkWhitelisted(sender.page, sender.frame,
@@ -71,18 +53,14 @@
       specificOnly ? ElemHide.SPECIFIC_ONLY : ElemHide.ALL_MATCHING
     );
   }
-  else
-  {
-    selectors = [];
-  }
 
-  if (selectors.length == 0 || userStylesheetsSupported &&
-      hideElements(sender.page.id, sender.frame.id, selectors))
+  if (!selectors || selectors.length == 0)
+    return {trace: false, inject: false};
+
+  if ('CSSOrigin' in chrome.extensionTypes)
   {
-    if (trace)
-      return {selectors, trace: true, inject: false};
-
-    return {trace: false, inject: false};
+    hideElements(sender.page.id, sender.frame.id, selectors);
+    return {selectors: trace ? selectors : null, trace, inject: false};
   }
 
   return {selectors, trace, inject: true};
@@ -90,5 +68,5 @@
 
 port.on("elemhide.injectSelectors", (msg, sender) =>
 {
-  return hideElements(sender.page.id, sender.frame.id, msg.selectors);
+  hideElements(sender.page.id, sender.frame.id, msg.selectors);
 });