Bug 1856795 - Remove redundant member init r=emilio

Done with:
./mach static-analysis check --checks="-*, readability-redundant-member-init" --fix .

https://clang.llvm.org/extra/clang-tidy/checks/readability/redundant-member-init.html

Differential Revision: https://phabricator.services.mozilla.com/D190002

dom/html/HTMLImageElement.cpp

@@ -84,8 +84,7 @@ class ImageLoadTask final : public MicroTaskRunnable {
  public:
   ImageLoadTask(HTMLImageElement* aElement, bool aAlwaysLoad,
                 bool aUseUrgentStartForChannel)
-      : MicroTaskRunnable(),
-        mElement(aElement),
+      : mElement(aElement),
         mAlwaysLoad(aAlwaysLoad),
         mUseUrgentStartForChannel(aUseUrgentStartForChannel) {
     mDocument = aElement->OwnerDoc();