Adds enableFeature() and isFeatureEnabled().
Adds the feature "StrictInitializationChecks".
Make pre-init property settability conditional: Setting a pre-init property after initialization is an error if Core feature StrictInitializationChecks is enabled. Otherwise it is a warning.
Adds enableFeature() and isFeatureEnabled(). Adds the feature "StrictInitializationChecks".
Make pre-init property settability conditional: Setting a pre-init property after initialization is an error if Core feature StrictInitializationChecks is enabled. Otherwise it is a warning.