[decompiler] fix missing casts issue (#573)

* fix casts issue

* fix bug

* one last small fix

test/decompiler/reference/engine/data/art-h_REF.gc

@@ -504,5 +504,5 @@
   )
 
 ;; failed to figure out what this is:
-(let ((v0-21 0))
+(let ((v0-37 0))
   )

test/decompiler/reference/engine/data/res-h_REF.gc

@@ -63,7 +63,5 @@
 (define *res-key-string* (new 'global 'string 64 (the-as string #f)))
 
 ;; failed to figure out what this is:
-(let ((v0-3 0))
+(let ((v0-4 0))
   )
-
-