[Android] Fix launch ActionUri will crash at runtime level

It's because for runtime usage, the NavigationHandler is using
the MixContext, Which needs FLAG_ACTIVITY_NEW_TASK to start
other Activity.

BUG=https://crosswalk-project.org/jira/browse/XWALK-551
Merge pull request #1217 from wang16/runtime_action_uri

[Android] Fix launch ActionUri will crash at runtime level