UiThreadUtil.assertX should only throw in DEBUG mode

Summary:
Turns out that `SoftAssertions.java` has always been a lie - it actually always throws exceptions. Migrate it to using `ReactSoftException`.

This file hasn't been touched at all since it was originally open-sourced, besides codemods!

Changelog: [Internal]

Reviewed By: mdvacca

Differential Revision: D18336020

fbshipit-source-id: cba3db25a9f9d61325dd3f7843e92e984ae56281

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

@@ -20,26 +20,32 @@ public class SoftAssertions {
   /**
    * Throw {@link AssertionException} with a given message. Use this method surrounded with {@code
    * if} block with assert condition in case you plan to do string concatenation to produce the
-   * message.
+   * message. This logs an assertion with ReactSoftException, which decides whether or not to
+   * actually throw.
    */
   public static void assertUnreachable(String message) {
-    throw new AssertionException(message);
+    ReactSoftException.logSoftException("SoftAssertions", new AssertionException(message));
   }
 
   /**
    * Asserts the given condition, throwing an {@link AssertionException} if the condition doesn't
-   * hold.
+   * hold. This logs an assertion with ReactSoftException, which decides whether or not to actually
+   * throw.
    */
   public static void assertCondition(boolean condition, String message) {
     if (!condition) {
-      throw new AssertionException(message);
+      ReactSoftException.logSoftException("SoftAssertions", new AssertionException(message));
     }
   }
 
-  /** Asserts that the given Object isn't null, throwing an {@link AssertionException} if it was. */
+  /**
+   * Asserts that the given Object isn't null, throwing an {@link AssertionException} if it was.
+   * This logs an assertion with ReactSoftException, which decides whether or not to actually throw.
+   */
   public static <T> T assertNotNull(@Nullable T instance) {
     if (instance == null) {
-      throw new AssertionException("Expected object to not be null!");
+      ReactSoftException.logSoftException(
+          "SoftAssertions", new AssertionException("Expected object to not be null!"));
     }
     return instance;
   }