- removed unused constant from ScreenLockHelper class
- used getProperty method of ITestDevice, instead of executeShellCommand
- modified BuildCheckTest to reflect use of 'getProperty' method above
- placed target preparer for Wifi check above apk installer, so apk
isn't installed until precondition check has passed
- removed unused imports in net module's PreconditionsTest
- added Wifi precondition check to content, text, webkit & widget modules
bug:23939594
Change-Id: I125b9937b974d142c0d2343f584516bfc713787a
c75c7e30f6