Delete wasm/many-memories.window.js WPT test

Testing for a specific number is causing problems and determining the right
number is problematic in general, as running out of memory is always a
legitimate possiblity. See https://github.com/WebAssembly/design/issues/1167 for
more discussion. In light of this, it's best to just remove the test.

Bug: 
Change-Id: I66e248c8ab851bca0c54fa6fe13b6e93e55f1264
Reviewed-on: https://chromium-review.googlesource.com/851081
Commit-Queue: Brad Nelson <bradnelson@chromium.org>
Reviewed-by: Brad Nelson <bradnelson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547333}

third_party/WebKit/LayoutTests/external/wpt/wasm/many-memories.window.js

-// Copyright 2017 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// This test makes sure browsers behave reasonably when asked to allocate a
-// larger number of WebAssembly.Memory objects at once.
-test(function() {
-  let memories = [];
-  try {
-    for (let i = 0; i < 20; i++) {
-      memories.push(new WebAssembly.Memory({initial: 1}));
-    }
-  } catch (e) {
-    if (e instanceof RangeError) {
-      return;
-    }
-    throw e;
-  }
-}, "WebAssembly#CreateManyMemories");