Media: Fall back to GD when loading URL in HHVM Imagick.

HHVM does not currently support loading URLs in its port of Imagick.
Fixes `test_wp_crop_image_url()` failure introduced in [36916].

See #35973.

git-svn-id: https://develop.svn.wordpress.org/trunk@36996 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-image-editor-imagick.php

@@ -84,6 +84,11 @@ class WP_Image_Editor_Imagick extends WP_Image_Editor {
 			return false;
 		}
 
+		// HHVM Imagick does not support loading from URL, so fail to allow fallback to GD.
+		if ( defined( 'HHVM_VERSION' ) && isset( $args['path'] ) && preg_match( '|^https?://|', $args['path'] ) ) {
+			return false;
+		}
+
 		return true;
 	}