no need for string->immutable-string when creating exceptions

svn: r5372

original commit: 19c33a8e2abba847bb5fa0ad5b7382ce03c583b2

collects/framework/private/preferences.ss

@@ -196,13 +196,12 @@ the state transitions / contracts are:
        ps
        vs
        fail-func)))
-    
-  
+
   (define (raise-unknown-preference-error sym fmt . args)
     (raise (exn:make-unknown-preference
-            (string->immutable-string (string-append (format "~a: " sym) (apply format fmt args)))
+            (string-append (format "~a: " sym) (apply format fmt args))
             (current-continuation-marks))))
-  
+
   ;; unmarshall-pref : symbol marshalled -> any
   ;; unmarshalls a preference read from the disk
   (define (unmarshall-pref p data)

collects/mred/private/mritem.ss

@@ -64,9 +64,9 @@
 		    (lambda (l)
 		      ((label-checker)
 		       '(method control<%> set-label) l)
-		      (let ([l (if (string? l) 
-				   (string->immutable-string l)
-				   l)])
+		      (let ([l (if (string? l)
+                                 (string->immutable-string l)
+                                 l)])
 			(send wx set-label l)
 			(set! label l))))])
       (public

collects/mred/private/mrpanel.ss

@@ -130,7 +130,7 @@
       (public
 	[get-number (lambda () (length save-choices))]
 	[append (entry-point
-		 (lambda (n) 
+		 (lambda (n)
 		   (check-label-string '(method tab-panel% append) n)
 		   (let ([n (string->immutable-string n)])
 		     (set! save-choices (list-append save-choices (list n)))