Makes Throwable.backingJsObject to not rely on exports.

Change-Id: Iae5997b7bd49b205aa40e6c9999cdef2024ad535
diff --git a/user/BUILD b/user/BUILD
index 05209c3..41e2e6e 100644
--- a/user/BUILD
+++ b/user/BUILD
@@ -66,6 +66,8 @@
         ],
         exclude = [
             "src/com/google/gwt/junit/**/*.java",  # see gwt-testing
+            "**/ConsoleLogger.java", # relies on internal APIs
+            "**/SuperDevModeLogger.java", # relies on ConsoleLogger
             "**/EmulatedCharset.java",
             "**/HashCodes.java",  # relies on java8 only APIs
             "**/RunStyleSelenium.java",