stdlib: Remove workaround for rdar://15520519, resolving ABI FIXME#141

Author: slavapestov

stdlib/public/core/ContiguousArrayBuffer.swift

@@ -59,13 +59,15 @@ internal var _emptyArrayStorage : _EmptyArrayStorage {
     Builtin.addressof(&_swiftEmptyArrayStorage))
 }
 
-// FIXME(ABI)#141 : This whole class is a workaround for
-// <rdar://problem/18560464> Can't override generic method in generic
-// subclass.  If it weren't for that bug, we'd override
-// _withVerbatimBridgedUnsafeBuffer directly in
-// _ContiguousArrayStorage<Element>.
-// rdar://problem/19341002
-class _ContiguousArrayStorage1 : _ContiguousArrayStorageBase {
+// The class that implements the storage for a ContiguousArray<Element>
+@_versioned
+final class _ContiguousArrayStorage<Element> : _ContiguousArrayStorageBase {
+
+  deinit {
+    _elementPointer.deinitialize(count: countAndCapacity.count)
+    _fixLifetime(self)
+  }
+
 #if _runtime(_ObjC)
   /// If the `Element` is bridged verbatim, invoke `body` on an
   /// `UnsafeBufferPointer` to the elements and return the result.
@@ -82,28 +84,7 @@ class _ContiguousArrayStorage1 : _ContiguousArrayStorageBase {
 
   /// If `Element` is bridged verbatim, invoke `body` on an
   /// `UnsafeBufferPointer` to the elements.
-  internal func _withVerbatimBridgedUnsafeBufferImpl(
-    _ body: (UnsafeBufferPointer<AnyObject>) throws -> Void
-  ) rethrows {
-    _sanityCheckFailure(
-      "Must override _withVerbatimBridgedUnsafeBufferImpl in derived classes")
-  }
-#endif
-}
-
-// The class that implements the storage for a ContiguousArray<Element>
-@_versioned
-final class _ContiguousArrayStorage<Element> : _ContiguousArrayStorage1 {
-
-  deinit {
-    _elementPointer.deinitialize(count: countAndCapacity.count)
-    _fixLifetime(self)
-  }
-
-#if _runtime(_ObjC)
-  /// If `Element` is bridged verbatim, invoke `body` on an
-  /// `UnsafeBufferPointer` to the elements.
-  internal final override func _withVerbatimBridgedUnsafeBufferImpl(
+  internal final func _withVerbatimBridgedUnsafeBufferImpl(
     _ body: (UnsafeBufferPointer<AnyObject>) throws -> Void
   ) rethrows {
     if _isBridgedVerbatimToObjectiveC(Element.self) {