qt5.qtwebengine: refactor more things to use patches instead of substituteInPlace

qt59.qtwebengine doesn't need those fixes (probably since the recent
minor version bump)

pkgs/development/libraries/qt-5/5.11/default.nix

@@ -67,6 +67,7 @@ let
       ++ optionals stdenv.isDarwin [
         ./qtwebengine-darwin-no-platform-check.patch
         ./qtwebengine-darwin-sdk-10.10.patch
+        ./qtwebengine-darwin-old-sdk.patch
       ];
     qtwebkit = [ ./qtwebkit.patch ]
       ++ optionals stdenv.isDarwin [

pkgs/development/libraries/qt-5/5.11/qtwebengine-darwin-old-sdk.patch

@@ -0,0 +1,21 @@
+diff --git a/src/3rdparty/chromium/third_party/webrtc/sdk/objc/Framework/Classes/Common/RTCFieldTrials.mm b/src/3rdparty/chromium/third_party/webrtc/sdk/objc/Framework/Classes/Common/RTCFieldTrials.mm
+--- a/src/3rdparty/chromium/third_party/webrtc/sdk/objc/Framework/Classes/Common/RTCFieldTrials.mm
++++ b/src/3rdparty/chromium/third_party/webrtc/sdk/objc/Framework/Classes/Common/RTCFieldTrials.mm
+@@ -45,7 +45,7 @@ NSString *RTCFieldTrialTrendlineFilterValue(
+   return [NSString stringWithFormat:format, windowSize, smoothingCoeff, thresholdGain];
+ }
+ 
+-void RTCInitFieldTrialDictionary(NSDictionary<NSString *, NSString *> *fieldTrials) {
++void RTCInitFieldTrialDictionary(NSDictionary *fieldTrials) {
+   if (!fieldTrials) {
+     RTCLogWarning(@"No fieldTrials provided.");
+     return;
+diff --git a/src/3rdparty/chromium/third_party/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCFieldTrials.h b/src/3rdparty/chromium/third_party/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCFieldTrials.h
+--- a/src/3rdparty/chromium/third_party/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCFieldTrials.h
++++ b/src/3rdparty/chromium/third_party/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCFieldTrials.h
+@@ -40,4 +40,4 @@ RTC_EXTERN NSString *RTCFieldTrialTrendlineFilterValue(
+  *  Must be called before any other call into WebRTC. See:
+  *  webrtc/system_wrappers/include/field_trial_default.h
+  */
+-RTC_EXTERN void RTCInitFieldTrialDictionary(NSDictionary<NSString *, NSString *> *fieldTrials);
++RTC_EXTERN void RTCInitFieldTrialDictionary(NSDictionary *fieldTrials);

pkgs/development/libraries/qt-5/modules/qtwebengine.nix

@@ -70,20 +70,6 @@ qtModule {
       substituteInPlace src/core/config/mac_osx.pri \
         --replace /usr ${stdenv.cc}
     ''
-    # TODO remove when new Apple SDK is in
-    + (if lib.versionOlder qtCompatVersion "5.11" then ''
-    substituteInPlace src/3rdparty/chromium/base/mac/foundation_util.mm \
-      --replace "NSArray<NSString*>*" "NSArray*"
-    substituteInPlace src/3rdparty/chromium/base/mac/sdk_forward_declarations.h \
-      --replace "NSDictionary<VNImageOption, id>*" "NSDictionary*" \
-      --replace "NSArray<VNRequest*>*" "NSArray*" \
-      --replace "typedef NSString* VNImageOption NS_STRING_ENUM" "typedef NSString* VNImageOption"
-    '' else ''
-    substituteInPlace src/3rdparty/chromium/third_party/webrtc/sdk/objc/Framework/Classes/Common/RTCFieldTrials.mm \
-      --replace "NSDictionary<NSString *, NSString *> *" "NSDictionary*"
-    substituteInPlace src/3rdparty/chromium/third_party/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCFieldTrials.h \
-      --replace "NSDictionary<NSString *, NSString *> *" "NSDictionary*"
-    '')
     + ''
 
     cat <<EOF > src/3rdparty/chromium/build/mac/find_sdk.py