Bug 1612891 - Use IgnoredErrorResult as the parsing easing error result. r=bzbarsky

IgnoredErrorResult works well as the auto suppressor class and it's
cleaner.

Differential Revision: https://phabricator.services.mozilla.com/D65810

--HG--
extra : moz-landing-system : lando

dom/animation/KeyframeUtils.cpp

@@ -373,17 +373,6 @@ static void GetKeyframeListFromKeyframeSequence(
   }
 }
 
-// The class to suppress the exception of parsing easing automatically.
-class MOZ_STACK_CLASS AutoErrorSuppressor final {
- public:
-  explicit AutoErrorSuppressor(ErrorResult& aErrorResult)
-      : mErrorResult(aErrorResult) {}
-  ~AutoErrorSuppressor() { mErrorResult.SuppressException(); }
-
- private:
-  ErrorResult& mErrorResult;
-};
-
 /**
  * Converts a JS object wrapped by the given JS::ForIfIterator to an
  * IDL sequence<Keyframe> and stores the resulting Keyframe objects in
@@ -394,11 +383,10 @@ static bool ConvertKeyframeSequence(JSContext* aCx, dom::Document* aDocument,
                                     const char* aContext,
                                     nsTArray<Keyframe>& aResult) {
   JS::Rooted<JS::Value> value(aCx);
-  ErrorResult parseEasingResult;
   // Parsing errors should only be reported after we have finished iterating
   // through all values. If we have any early returns while iterating, we should
-  // suppress parsing errors.
-  AutoErrorSuppressor AutoErrorSuppressor(parseEasingResult);
+  // ignore parsing errors.
+  IgnoredErrorResult parseEasingResult;
 
   for (;;) {
     bool done;