Bootstrap/Load: Ensure WP_Fatal_Error_Handler does not conflict with existing mechanisms treating fatal errors.

Prior to this change, resuming or activating a plugin or theme that is still broken would result in a redirect loop if in recovery mode. If outside recovery mode, it would cause the error template to be displayed.

Furthermore this applies to breaking a plugin or theme when editing from the backend.

Props aandrewdixon, azaozz, dhanukanuwan, henrywright, ocean90, ohiosierra, PandelisZ, xkon.
Fixes #46045, #46751.


git-svn-id: https://develop.svn.wordpress.org/trunk@45114 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/theme.php

@@ -859,6 +859,7 @@ function resume_theme( $theme, $redirect = '' ) {
 
 			// Load the theme's functions.php to test whether it throws a fatal error.
 			ob_start();
+			define( 'WP_SANDBOX_SCRAPING', true );
 			include $functions_path;
 			ob_clean();
 		}