Release React Native for Android

This is an early release and there are several things that are known
not to work if you're porting your iOS app to Android.

See the Known Issues guide on the website.

We will work with the community to reach platform parity with iOS.

ReactAndroid/src/main/java/com/facebook/react/bridge/SoftAssertions.java

@@ -0,0 +1,41 @@
+/**
+ * Copyright (c) 2015-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.bridge;
+
+import javax.annotation.Nullable;
+
+/**
+ * Utility class to make assertions that should not hard-crash the app but instead be handled by the
+ * Catalyst app {@link NativeModuleCallExceptionHandler}. See the javadoc on that class for
+ * more information about our opinion on when these assertions should be used as opposed to
+ * assertions that might throw AssertionError Throwables that will cause the app to hard crash.
+ */
+public class SoftAssertions {
+
+  /**
+   * Asserts the given condition, throwing an {@link AssertionException} if the condition doesn't
+   * hold.
+   */
+  public static void assertCondition(boolean condition, String message) {
+    if (!condition) {
+      throw new AssertionException(message);
+    }
+  }
+
+  /**
+   * Asserts that the given Object isn't null, throwing an {@link AssertionException} if it was.
+   */
+  public static <T> T assertNotNull(@Nullable T instance) {
+    if (instance == null) {
+      throw new AssertionException("Expected object to not be null!");
+    }
+    return instance;
+  }
+}