RFR(XS): 8168304: Make all of DependencyContext_test available in product mode.

[Evgeny Nikitin]

Hi, 


Bug: https://bugs.openjdk.java.net/browse/JDK-8168304 
Webrev: http://cr.openjdk.java.net/~iignatyev/enikitin/8168304/webrev.00/ 


The tests effectively had not been run in the product mode prior to the change (the function that allows querying the DependencyContext for whether the nmethod is dependent or not had not been present in the product mode). 


The DependencyContext's API has been extended by enabling said member function `is_dependent_nmethod` in the product mode, the unit test adjusted to utilise the function. 


The change had been tested via a full googletest run on 4 platforms (linux-x64, windows-x64, macosx-x64, sparcv9) 


Please review, 
/Evgeny Nikitin