Update the signature of debug_backtrace

the file and line keys might be missing for frames. This happens when the frame are calls originating from native code.

dictionaries/CallMap.php

@@ -1546,7 +1546,7 @@
 'dcgettext' => ['string', 'domain'=>'string', 'message'=>'string', 'category'=>'int'],
 'dcngettext' => ['string', 'domain'=>'string', 'singular'=>'string', 'plural'=>'string', 'count'=>'int', 'category'=>'int'],
 'deaggregate' => ['', 'object'=>'object', 'class_name='=>'string'],
-'debug_backtrace' => ['list<array{file:string,line:int,function:string,class?:class-string,object?:object,type?:string,args?:list}>', 'options='=>'int', 'limit='=>'int'],
+'debug_backtrace' => ['list<array{file?:string,line?:int,function:string,class?:class-string,object?:object,type?:string,args?:list}>', 'options='=>'int', 'limit='=>'int'],
 'debug_print_backtrace' => ['void', 'options='=>'int', 'limit='=>'int'],
 'debug_zval_dump' => ['void', 'value'=>'mixed', '...values='=>'mixed'],
 'debugger_connect' => [''],