[stdlib] Drop a couple bogus duplicate tests

Only the last of each set of dups gets run anyway.  See
https://bugs.swift.org/browse/SR-5362

Author: Dave Abrahams

validation-test/stdlib/StringViews.swift

@@ -211,88 +211,6 @@ tests.test("index-mapping/utf16-to-utf8") {
     summer.utf16.endIndex.samePosition(in: summer.utf8)!)
 }
 
-tests.test("index-mapping/utf8-to-unicode-scalar") {
-  // Define expectation separately to help the type-checker, which
-  // otherwise runs out of time solving.
-  let winterUtf8UnicodeScalars: [UnicodeScalar?] = [
-    UnicodeScalar(0x1f3c2), nil, nil, nil,
-    UnicodeScalar(0x2603), nil, nil,
-    UnicodeScalar(0x2745), nil, nil,
-    UnicodeScalar(0x2746), nil, nil,
-    UnicodeScalar(0x2744), nil, nil, UnicodeScalar(0xfe0e), nil, nil,
-    UnicodeScalar(0x26c4), nil, nil, UnicodeScalar(0xfe0f), nil, nil,
-    UnicodeScalar(0x2744), nil, nil, UnicodeScalar(0xfe0f), nil, nil
-  ]
-  
-  expectEqualSequence(
-    winterUtf8UnicodeScalars,
-    winter.utf8.indices.map {
-      i in i.samePosition(in: winter.unicodeScalars).map {
-        winter.unicodeScalars[$0]
-      }
-    }, sameValue: ==
-  )
-
-  expectNotNil(winter.utf8.endIndex.samePosition(in: winter.unicodeScalars))
-  expectEqual(
-    winter.unicodeScalars.endIndex,
-    winter.utf8.endIndex.samePosition(in: winter.unicodeScalars)!)
-  
-  expectEqualSequence(
-    summerBytes.map { UnicodeScalar($0) as UnicodeScalar? },
-    summer.utf8.indices.map {
-      i in i.samePosition(in: summer.unicodeScalars).map {
-        summer.unicodeScalars[$0]
-      }
-    }, sameValue: ==
-  )
-
-  expectNotNil(summer.utf8.endIndex.samePosition(in: summer.unicodeScalars))
-  expectEqual(
-    summer.unicodeScalars.endIndex,
-    summer.utf8.endIndex.samePosition(in: summer.unicodeScalars)!)
-}
-
-tests.test("index-mapping/utf16-to-unicode-scalar") {
-  let winterUtf16UnicodeScalars: [UnicodeScalar?] = [
-    UnicodeScalar(0x1f3c2), nil,
-    UnicodeScalar(0x2603), 
-    UnicodeScalar(0x2745), 
-    UnicodeScalar(0x2746), 
-    UnicodeScalar(0x2744), UnicodeScalar(0xfe0e),
-    UnicodeScalar(0x26c4), UnicodeScalar(0xfe0f),
-    UnicodeScalar(0x2744), UnicodeScalar(0xfe0f)
-  ]
-  
-  expectEqualSequence(
-    winterUtf16UnicodeScalars,
-    winter.utf16.indices.map {
-      i in i.samePosition(in: winter.unicodeScalars).map {
-        winter.unicodeScalars[$0]
-      }
-    }, sameValue: ==
-  )
-
-  expectNotNil(winter.utf16.endIndex.samePosition(in: winter.unicodeScalars))
-  expectEqual(
-    winter.unicodeScalars.endIndex,
-    winter.utf16.endIndex.samePosition(in: winter.unicodeScalars)!)
-  
-  expectEqualSequence(
-    summerBytes.map { UnicodeScalar($0) as UnicodeScalar? },
-    summer.utf16.indices.map {
-      i in i.samePosition(in: summer.unicodeScalars).map {
-        summer.unicodeScalars[$0]
-      }
-    }, sameValue: ==
-  )
-
-  expectNotNil(summer.utf16.endIndex.samePosition(in: summer.unicodeScalars))
-  expectEqual(
-    summer.unicodeScalars.endIndex,
-    summer.utf16.endIndex.samePosition(in: summer.unicodeScalars)!)
-}
-
 //===--- To UTF16 ---------------------------------------------------------===//
 tests.test("index-mapping/character-to-utf16") {
   expectEqualSequence(