Merge changes Id4fb7c99,I14dd4eb9,I37c2ece1,I7b4b084b,I78f1d4b3, ...

* changes:
  Move Trace to use trampolines
  Move back to jit code on trace removal
  Rewrite JVMTI method tracing to use trampolines
  Don't use StringFactory.newEmptyString in compiled code
  Ensure proxy methods are reported by instrumentation
  Correctly send MethodExit events from exception handlers
  Make instrumentation trampoline able to jump to jit code