Add test 1914 to gcstress known failures too.

This test also exhibits the class-less object problem.

Bug: 67707598
Bug: 67679263
Test: ./test.py --host -j50
Change-Id: I02e654b1d949ac4faf54eefa958cd2b57378310f
diff --git a/test/knownfailures.json b/test/knownfailures.json
index 56a06d6..47b2f22 100644
--- a/test/knownfailures.json
+++ b/test/knownfailures.json
@@ -1,7 +1,7 @@
 [
     {
-        "tests": "1939-proxy-frames",
-        "description": ["Test 1939 seems to consistently fail in gcstress on 64 bit with",
+        "tests": [ "1939-proxy-frames", "1914-get-local-instance" ],
+        "description": ["Test 1939 & 1914 seems to consistently fail in gcstress on 64 bit with",
                         "a proxy this object having no associated class!"],
         "variant": "gcstress",
         "bug": "http://b/67679263"