Adds the POC test to the existing javascriptengine_test instrumentation APK.

--- a/third_party/androidx_javascriptengine/BUILD.gn
+++ b/third_party/androidx_javascriptengine/BUILD.gn
@@ -86,9 +86,13 @@ instrumentation_test_apk("javascriptengine_test") {
   apk_name = "WebViewJsSandboxTestAppTest"
   android_manifest =
       "//android_webview/js_sandbox/javatests/AndroidManifest.xml"
-  sources = [ "src/androidTest/java/androidx/javascriptengine/WebViewJavaScriptSandboxTest.java" ]
+  sources = [
+    "src/androidTest/java/androidx/javascriptengine/JsSandboxIsolateUafTest.java",
+    "src/androidTest/java/androidx/javascriptengine/WebViewJavaScriptSandboxTest.java",
+  ]
   deps = [
     ":javascriptengine_java",
+    ":js_sandbox_aidl_java",
     "//third_party/android_deps:guava_android_java",
     "//third_party/androidx:androidx_core_core_java",
     "//third_party/androidx:androidx_test_core_java",