Should check the nullity of getActivity() in ParseLoginFragmentBase

[HTChang]

No description provided.

[HTChang]

To fix NPE

java.lang.NullPointerException
    at com.parse.ui.ParseLoginFragmentBase.isActivityDestroyed(ParseLoginFragmentBase.java:80)
    at com.parse.ui.ParseLoginFragment$4$1.done(ParseLoginFragment.java:252)
    at com.parse.LogInCallback.internalDone(LogInCallback.java:43)
    at com.parse.LogInCallback.internalDone(LogInCallback.java:29)
    at com.parse.Parse$6$1.run(Parse.java:973)
    at android.os.Handler.handleCallback(Handler.java:733)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:146)
    at android.app.ActivityThread.main(ActivityThread.java:5748)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
    at dalvik.system.NativeStart.main(Native Method)

[stanleyw]

Thank you for your contribution!

• Could we name the variable activity instead of act, for consistency with rest of this repo?
• Would you mind accepting the Facebook contributor license agreement so that we can give you proper attribution when we merge this in? https://developers.facebook.com/opensource/cla

[HTChang]

I've renamed the variable and willing to accept Facebook contributor license agreement.
Thanks.

[facebook-github-bot]

@HTChang updated the pull request.