qt5.qtwebengine: 5.15.2 -> 5.15.3-a059e740

This updates the base chromium branch from 83 to 87, which fixes
approximately a few hundreds CVEs.

pkgs/development/libraries/qt-5/5.15/default.nix

@@ -16,7 +16,7 @@ top-level attribute to `top-level/all-packages.nix`.
 
 {
   newScope,
-  lib, stdenv, fetchurl, fetchpatch, fetchFromGitHub, makeSetupHook, makeWrapper,
+  lib, stdenv, fetchurl, fetchpatch, fetchgit, fetchFromGitHub, makeSetupHook, makeWrapper,
   bison, cups ? null, harfbuzz, libGL, perl,
   gstreamer, gst-plugins-base, gtk3, dconf,
   llvmPackages_5,
@@ -48,6 +48,27 @@ let
       };
       version = "5.212.0-alpha4";
     };
+
+    # Even if developed in the public, QtWebEngine does not have official
+    # releases or new tags since the Qt company made 5.15.3 proprietary.
+    # Apparently they care more about licensing than the security of their users.
+    # See https://lists.qt-project.org/pipermail/interest/2021-March/036387.html
+    qtwebengine =
+      let
+        branchName = "5.15.3";
+        rev = "a059e7404a6db799f4da0ad696e65ae9c854b4b0";
+      in
+      {
+        version = "${branchName}-${lib.substring 0 8 rev}";
+
+        src = fetchgit {
+          url = "https://github.com/qt/qtwebengine.git";
+          sha256 = "19l1i4sk3pvnwbvz5s97jchqawfz8k1xmjza29bgvkp1zz96r0jx";
+          inherit rev branchName;
+          fetchSubmodules = true;
+          leaveDotGit = true;
+        };
+      };
   };
 
   patches = {
@@ -83,11 +104,16 @@ let
     qtdeclarative = [ ./qtdeclarative.patch ];
     qtscript = [ ./qtscript.patch ];
     qtserialport = [ ./qtserialport.patch ];
-    qtwebengine = [ ]
-      ++ optionals stdenv.isDarwin [
-        ./qtwebengine-darwin-no-platform-check.patch
-        ./qtwebengine-mac-dont-set-dsymutil-path.patch
-      ];
+    qtwebengine = [
+      # Fix crashes with non en_US.UTF-8 locales
+      (fetchpatch {
+        url = "https://github.com/qt/qtwebengine/commit/199ea00a9eea13315a652c62778738629185b059.patch";
+        sha256 = "1b5k2g1v8913cvsgvp6ja4mcprjlk5vcwqzi0p1qq7b1wyi4f0g2";
+      })
+    ] ++ optionals stdenv.isDarwin [
+      ./qtwebengine-darwin-no-platform-check.patch
+      ./qtwebengine-mac-dont-set-dsymutil-path.patch
+    ];
     qtwebkit = [
       (fetchpatch {
         name = "qtwebkit-bison-3.7-build.patch";