RFR (s) 8033735: make Throwable.backtrace visible to Class.getDeclaredField again

[Coleen Phillimore]

Summary: removed old hack to workaround an old crash.

Tested with given test case and hotspot runtime tests and 
jdk/test/java/lang/Throwable tests (and selected other jdk tests).

open webrev at http://cr.openjdk.java.net/~coleenp/8033735.01/webrev
bug link https://bugs.openjdk.java.net/browse/JDK-8033735

Thanks,
Coleen