Fix prototype of anonymous records

src/fable-library/Types.js

@@ -216,7 +216,7 @@ Record.prototype.CompareTo = function(other) {
 };
 
 export function anonRecord(o) {
-  return Object.assign(Object.create(Record), o);
+  return Object.assign(Object.create(Record.prototype), o);
 }
 
 export const FSharpRef = declare(function FSharpRef(contents) {

src/quicktest/QuickTest.fs

@@ -49,11 +49,3 @@ let testCaseAsync msg f =
 // to Fable.Tests project. For example:
 // testCase "Addition works" <| fun () ->
 //     2 + 2 |> equal 4
-
-let makeAnonRec() =
-    {| X = 5; Y = "Foo"; F = fun x y -> x + y |}
-
-testCase "Anonymous records work" <| fun () ->
-    let r = makeAnonRec()
-    sprintf "Tell me %s %i times" r.Y (r.F r.X 3)
-    |> equal "Tell me Foo 8 times"

tests/Main/RecordTypeTests.fs

@@ -43,6 +43,11 @@ let tests =
         let r = makeAnonRec()
         sprintf "Tell me %s %i times" r.Y (r.F r.X 3)
         |> equal "Tell me Foo 8 times"
+        let x = {| Foo = "baz"; Bar = 23 |}
+        let y = {| Foo = "baz" |}
+        x = {| y with Bar = 23 |} |> equal true
+        // x = {| y with Baz = 23 |} |> equal true // Doesn't compile
+        x = {| y with Bar = 14 |} |> equal false
 #endif
 
     testCase "Recursive record does not cause issues" <| fun () ->