Properly "handle" MOJO_RESULT_BUSY in a few flaces.

mojo/public/cpp/utility/lib/run_loop.cc

Index: mojo/public/cpp/utility/lib/run_loop.cc
diff --git a/mojo/public/cpp/utility/lib/run_loop.cc b/mojo/public/cpp/utility/lib/run_loop.cc
index f5547201e1c3f30f836d2f1d71c99b0137f22e95..f68ad79a08917b9928eba8716baa494c57d6ed2a 100644
--- a/mojo/public/cpp/utility/lib/run_loop.cc
+++ b/mojo/public/cpp/utility/lib/run_loop.cc
@@ -169,6 +169,11 @@ bool RunLoop::Wait(bool non_blocking) {
       handler->OnHandleReady(handle);
       return true;
     case MOJO_RESULT_INVALID_ARGUMENT:
+    case MOJO_RESULT_CANCELLED:
+    case MOJO_RESULT_BUSY:
+      // These results indicate a bug in "our" code (e.g., race conditions).
+      assert(false);
+      // Fall through.
     case MOJO_RESULT_FAILED_PRECONDITION:
       // Remove the handle first, this way if OnHandleError() tries to remove
       // the handle our iterator isn't invalidated.