From cf10dc032eaae6ae6ac77a12659de33263204d86 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emilio=20Cobos=20=C3=81lvarez?= <emilio@crisal.io>
Date: Thu, 21 Jun 2018 20:08:40 +0200
Subject: [PATCH] Bug 1470035: Don't reparse cssom sheets, and warn about the
 reparse being lossy. r=jryans

MozReview-Commit-ID: 7j7Tyej0oYn

--HG--
extra : rebase_source : dd5966a2a9779175f88ae7448aa337155fe65dcd
---
 .../server/actors/targets/browsing-context.js | 21 +++++++++++++++++--
 .../locales/en-US/browsing-context.properties |  7 +++++++
 2 files changed, 26 insertions(+), 2 deletions(-)
 create mode 100644 devtools/shared/locales/en-US/browsing-context.properties

diff --git a/devtools/server/actors/targets/browsing-context.js b/devtools/server/actors/targets/browsing-context.js
index 6e5c3da174aa..85bae4b0b590 100644
--- a/devtools/server/actors/targets/browsing-context.js
+++ b/devtools/server/actors/targets/browsing-context.js
@@ -35,6 +35,10 @@ const InspectorUtils = require("InspectorUtils");
 
 const EXTENSION_CONTENT_JSM = "resource://gre/modules/ExtensionContent.jsm";
 
+const { LocalizationHelper } = require("devtools/shared/l10n");
+const STRINGS_URI = "devtools/shared/locales/browsing-context.properties";
+const L10N = new LocalizationHelper(STRINGS_URI);
+
 const { ActorClassWithSpec, Actor } = require("devtools/shared/protocol");
 const { browsingContextTargetSpec } = require("devtools/shared/specs/targets/browsing-context");
 
@@ -1055,11 +1059,24 @@ const browsingContextTargetPrototype = {
       // Shadow DOM / XBL.
       const sheets =
         InspectorUtils.getAllStyleSheets(docShell.document, /* documentOnly = */ true);
+      const promises = [];
       for (const sheet of sheets) {
-        getSheetText(sheet, this._consoleActor).then(text => {
+        if (InspectorUtils.hasRulesModifiedByCSSOM(sheet)) {
+          continue;
+        }
+        // Reparse the sheet so that we see the existing errors.
+        promises.push(getSheetText(sheet, this._consoleActor).then(text => {
           InspectorUtils.parseStyleSheet(sheet, text, /* aUpdate = */ false);
-        });
+        }));
       }
+
+      Promise.all(promises).then(() => {
+        this.logInPage({
+          text: L10N.getStr("cssSheetsReparsedWarning"),
+          category: "CSS Parser",
+          flags: Ci.nsIScriptError.warningFlag,
+        });
+      });
     }
 
     return {};
diff --git a/devtools/shared/locales/en-US/browsing-context.properties b/devtools/shared/locales/en-US/browsing-context.properties
new file mode 100644
index 000000000000..1180496c0515
--- /dev/null
+++ b/devtools/shared/locales/en-US/browsing-context.properties
@@ -0,0 +1,7 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE (cssSheetsReparsedWarning): The warning
+# to show after the CSS message filter has been toggled on.
+cssSheetsReparsedWarning=Stylesheets without CSSOM changes reparsed to check for errors. Refresh the page to also see errors from stylesheets changed from CSSOM and from style attributes.