Revert "[stdlib] NSStringAPI: add stringByApplyingTransform"

This is breaking NSStringAPI.swift on the bots.

Swift SVN r28084

stdlib/public/SDK/Foundation/NSStringAPI.swift

@@ -1468,13 +1468,5 @@ extension String {
     try self._ns.writeToURL(
       url, atomically: useAuxiliaryFile, encoding: enc)
   }
-
-  @availability(iOS, introduced=9.0)
-  @availability(OSX, introduced=10.11)
-  public func stringByApplyingTransform(
-    transform: String, reverse: Bool
-  ) -> String? {
-    return _ns.stringByApplyingTransform(transform, reverse: reverse)
-  }
 }
 

test/1_stdlib/NSStringAPI.swift

@@ -1878,16 +1878,6 @@ NSStringAPIs.test("copy construction") {
   expectEqual(expected, y as String)
 }
 
-NSStringAPIs.test("stringByApplyingTransform(_:reverse:)") {
-  let veryKewl = "tre\u{300}s k\u{fc}hl"
-  if #available(OSX 10.11, iOS 9.0, *) {
-    expectEqual(
-      "tres kuhl",
-      veryKewl.stringByApplyingTransform(
-        NSStringTransformStripDiacritics, reverse: false))
-  }
-}
-
 var CStringTests = TestSuite("CStringTests")
 
 func getNullCString() -> UnsafeMutablePointer<CChar> {