Remove iOS platform check for running devtools

Summary:
Currently, DevTools only work under ios (although this is undocumented!),
because the JavaScriptEngine initialization process skips setupDevTools() on
android.

DevTools work fine with Android, as tested on 0.26, 0.27, and 0.28 using
Nuclide's inspector.

For reference, the relevant issue on react-devtools.
Closes https://github.com/facebook/react-native/pull/8095

Reviewed By: bestander

Differential Revision: D3492788

Pulled By: andreicoman11

fbshipit-source-id: 1eda9196d7125da19a8d7baaab22b61b744ca629

ReactAndroid/src/androidTest/java/com/facebook/react/testing/FakeWebSocketModule.java

@@ -0,0 +1,52 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc.
+ * All rights reserved.
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+package com.facebook.react.testing;
+
+import javax.annotation.Nullable;
+
+import com.facebook.react.bridge.BaseJavaModule;
+import com.facebook.react.bridge.ReactMethod;
+import com.facebook.react.bridge.ReadableArray;
+import com.facebook.react.bridge.ReadableMap;
+
+/**
+ * Dummy implementation of storage module, used for testing
+ */
+public final class FakeWebSocketModule extends BaseJavaModule {
+
+  @Override
+  public String getName() {
+    return "WebSocketModule";
+  }
+
+  @Override
+  public boolean canOverrideExistingModule() {
+    return true;
+  }
+
+  @ReactMethod
+  public void connect(
+    final String url,
+    @Nullable final ReadableArray protocols,
+    @Nullable final ReadableMap headers,
+    final int id) {
+  }
+
+  @ReactMethod
+  public void close(int code, String reason, int id) {
+  }
+
+  @ReactMethod
+  public void send(String message, int id) {
+  }
+
+  @ReactMethod
+  public void sendBinary(String base64String, int id) {
+  }
+}

ReactAndroid/src/androidTest/java/com/facebook/react/testing/ReactInstanceSpecForTest.java

@@ -9,6 +9,7 @@
 package com.facebook.react.testing;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 
 import android.annotation.SuppressLint;
@@ -26,7 +27,8 @@ import com.facebook.react.ReactPackage;
 @SuppressLint("JavatestsIncorrectFolder")
 public class ReactInstanceSpecForTest {
 
-  private final List<NativeModule> mNativeModules = new ArrayList<>();
+  private final List<NativeModule> mNativeModules =
+    new ArrayList<NativeModule>(Arrays.asList(new FakeWebSocketModule()));
   private final List<Class<? extends JavaScriptModule>> mJSModuleSpecs = new ArrayList<>();
   private final List<ViewManager> mViewManagers = new ArrayList<>();
   private ReactPackage mReactPackage = null;