compare Set and Dictionary by address for equality

as noted in the comment, the native storage version of Set and Dictionary can
be considered equal if their Owner object have the same address. This should
speed up == by quite a bit in those cases.

use === for equality of HashedCollection owner

Author: dduan

stdlib/public/core/HashedCollections.swift.gyb

@@ -678,8 +678,10 @@ public func == <Element : Hashable>(lhs: Set<Element>, rhs: Set<Element>) -> Boo
   case (.Native(let lhsNativeOwner), .Native(let rhsNativeOwner)):
     let lhsNative = lhsNativeOwner.nativeStorage
     let rhsNative = rhsNativeOwner.nativeStorage
-    // FIXME(performance): early exit if lhs and rhs reference the same
-    // storage?
+
+    if lhsNativeOwner === rhsNativeOwner {
+        return true
+    }
 
     if lhsNative.count != rhsNative.count {
       return false
@@ -1184,8 +1186,10 @@ public func == <Key : Equatable, Value : Equatable>(
   case (.Native(let lhsNativeOwner), .Native(let rhsNativeOwner)):
     let lhsNative = lhsNativeOwner.nativeStorage
     let rhsNative = rhsNativeOwner.nativeStorage
-    // FIXME(performance): early exit if lhs and rhs reference the same
-    // storage?
+
+    if lhsNativeOwner === rhsNativeOwner {
+        return true
+    }
 
     if lhsNative.count != rhsNative.count {
       return false