fix poor wording

text/0000-nonparametric-dropck.md

@@ -464,7 +464,7 @@ a function `fn foo()`, would mean two things:
 All `fn drop` methods would be required to be `#[unspecialized]`.
 
 It is the second bullet that makes this an ad-hoc effect system: it provides
-a recursive property that ensures that during the extent of the call to `foo`,
+a recursive property ensuring that during the extent of the call to `foo`,
 we will never invoke a function marked as `default`.
 
 It is also this second bullet that represents a signficant burden on