Make the application lifecycle does not affect SchedulerBinding.scheduleForcedFrame. (#97468)

Author: ColdPaleLight

packages/flutter/lib/src/scheduler/binding.dart

@@ -818,11 +818,6 @@ mixin SchedulerBinding on BindingBase {
   /// Consider using [scheduleWarmUpFrame] instead if the goal is to update the
   /// rendering as soon as possible (e.g. at application startup).
   void scheduleForcedFrame() {
-    // TODO(chunhtai): Removes the if case once the issue is fixed
-    // https://github.com/flutter/flutter/issues/45131
-    if (!framesEnabled)
-      return;
-
     if (_hasScheduledFrame)
       return;
     assert(() {

packages/flutter/test/widgets/binding_test.dart

@@ -177,10 +177,9 @@ void main() {
     tester.binding.scheduleFrame();
     expect(tester.binding.hasScheduledFrame, isFalse);
 
-    // TODO(chunhtai): fix this test after workaround is removed
-    // https://github.com/flutter/flutter/issues/45131
     tester.binding.scheduleForcedFrame();
-    expect(tester.binding.hasScheduledFrame, isFalse);
+    expect(tester.binding.hasScheduledFrame, isTrue);
+    await tester.pump();
 
     int frameCount = 0;
     tester.binding.addPostFrameCallback((Duration duration) {