Name and label changes for closure parameters (for review only) (#2981)

Implement SE-0118 Name and label changes for closure parameters

[SE-0118](https://github.com/apple/swift-evolution/blob/master/proposals/0118-closure-parameter-names-and-labels.md)

validation-test/stdlib/UnicodeTrie.swift.gyb

@@ -101,7 +101,7 @@ class NonContiguousNSString : NSString {
       from: UTF32.self,
       to: UTF16.self,
       stoppingOnError: true,
-      sendingOutputTo: output)
+      into: output)
     expectFalse(hadError)
     self.init(encoded)
   }